Vegetarian Lentil Shepherds Pie

The first time I made this, it wasn't because I was planning to go vegetarian—it was because my neighbor brought over a bag of sweet potatoes from her garden and I wanted to use them for something more interesting than roasting. I'd been craving shepherd's pie, that cozy British comfort food, but decided to flip it by swapping the meat for lentils. One pot simmering away, the kitchen filling with the smell of thyme and roasted vegetables, and suddenly I understood why this dish deserves its own place at the table.

I made this for a dinner party where half my guests were vegetarian and half weren't, and honestly, nobody missed the beef. We sat around the table passing dishes of salad, and someone asked for seconds of the pie before finishing their first plate—that's when I knew I'd created something worth repeating. The golden-brown sweet potato top caught the light, and my friend asked if I could teach them how to make it. That's when I realized this recipe had become part of my kitchen storytelling.

Ingredients

• Sweet potatoes, 900 g (2 lbs), peeled and chunked: These soften quickly and create a naturally creamy mash without needing too much dairy; their slight sweetness becomes the dish's secret weapon.
• Unsalted butter, 2 tbsp: Use real butter here—it adds a richness that plant-based oils can match but not replace, though olive oil works beautifully if you're going vegan.
• Milk, 60 ml (¼ cup): Just enough to loosen the mash into something spreadable; I usually warm it slightly so it incorporates more smoothly.
• Brown or green lentils, 150 g (1 cup), rinsed: Green lentils hold their shape better than red ones, which means your filling stays textured rather than turning into mush.
• Vegetable broth, 500 ml (2 cups): This is where flavor lives; use something with actual seasoning, not the bland stuff, because it seasons the lentils as they cook.
• Tomato paste, 2 tbsp: This concentrates into something rich and umami-forward, deepening the whole filling in just a small amount.
• Olive oil, 2 tbsp: For sautéing the aromatics; good quality makes a difference in how golden everything becomes.
• Yellow onion, 1 medium, finely chopped: The foundation flavor that builds when it softens; don't skip this step of letting it cook properly.
• Garlic, 2 cloves, minced: Adds depth without overwhelming; mince it fine so it distributes evenly through the filling.
• Carrots, 2 medium, diced: These provide natural sweetness and texture; dice them small enough to cook through in the time given.
• Celery stalks, 2, diced: Often overlooked, but this is what makes the filling taste like proper home cooking rather than something rushed.
• Soy sauce or tamari, 1 tbsp: This adds savory depth without needing to taste overtly salty; it's the quiet ingredient that makes people ask what's in it.
• Dried thyme, 1 tsp: Woody and herbaceous, this ties everything back to the British origins of the dish.
• Dried rosemary, 1 tsp: Use a light hand here because rosemary can overpower; dried works better than fresh because it mellows as it simmers.
• Bay leaf, 1: Simmers quietly in the background, adding a subtle aromatic note—remember to fish it out before serving.
• Frozen peas, 120 g (1 cup): These go in at the end for color and sweetness; frozen peas are honestly better than fresh here because they're picked at peak ripeness.
• Salt and black pepper: Taste as you go; you'll need more seasoning than you think because lentils absorb flavors.

Instructions

Heat your oven and start the sweet potatoes:

Preheat to 200°C (400°F) so it's ready when you need it. Cut your sweet potatoes into chunks about the size of walnuts—this speeds up cooking without turning them to mush. Drop them into salted boiling water and let them simmer for 15 to 20 minutes until a fork slides through easily.

Build the filling's flavor base:

While potatoes cook, warm olive oil in your skillet over medium heat. Add chopped onion and let it soften for a few minutes before adding garlic, carrots, and celery; you'll hear them sizzle and start to soften after about 5 to 7 minutes. Don't rush this—the vegetables release their sweetness when given time.

Bring the lentils to life:

Stir in your rinsed lentils, tomato paste, soy sauce, thyme, rosemary, bay leaf, and vegetable broth. The mixture should bubble gently at the edges; cover and let it simmer for 25 to 30 minutes, stirring now and then. You'll know it's done when the lentils are tender and the broth has mostly soaked in, leaving things saucy but not soupy.

Make the sweet potato mash:

Drain your cooked potatoes well—excess water ruins the mash. Mash them with butter and warm milk until creamy and smooth, then season generously with salt and pepper. The mash should taste good enough to eat on its own.

Finish and assemble:

Remove the bay leaf from the lentil filling and stir in the frozen peas. Taste and adjust seasoning—this is important because lentils can taste bland without proper salt. Pour the filling into your baking dish and spread the sweet potato mash evenly over top, right to the edges so it gets golden.

Bake until golden:

Bake for 20 minutes until the top takes on a warm golden-brown color. Let it rest for 5 minutes before serving so everything sets slightly and holds together when you scoop it out.

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There's something about spooning into this dish and hitting that layer of warm, creamy sweet potato before reaching the rich, earthy lentil filling that feels like being looked after. It's the kind of food that makes you slow down, that tastes like someone cares about you eating well.

Why Sweet Potato Instead of Regular

Regular potatoes are fine, but sweet potatoes bring their own subtle sweetness that plays beautifully against the savory lentil filling—it's less about replacing something and more about discovering what works even better. The color alone makes the dish feel more celebratory, and nutritionally, sweet potatoes pack more fiber and nutrients so you're eating something genuinely nourishing. I've tried both, and sweet potato wins every time because it tastes like intention rather than habit.

Making It Vegan

Swap the butter for olive oil and the milk for plant-based alternatives—almond, oat, or cashew cream all work, though cashew cream creates the creamiest result. The filling is already vegan if you use vegetable broth, so you're really just adjusting the mash, and honestly, nobody can tell the difference. I've made it both ways for mixed groups and watched people eat the vegan version without realizing until I mentioned it.

Serving and Storage

Serve it straight from the baking dish with a sharp green salad on the side to cut through the richness—something peppery like arugula or mustard greens makes everything taste brighter. This dish actually improves the next day as flavors settle, and it reheats beautifully covered in foil at 180°C (350°F) for about 15 minutes until warmed through.

• Leftovers keep for 3 to 4 days in the refrigerator and freeze beautifully for up to 3 months.
• You can assemble the whole dish ahead of time and bake it when you're ready to eat, which makes weeknight cooking feel less frantic.
• If you find the filling too thick when reheating, stir in a splash of vegetable broth to loosen it slightly.

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This is the kind of dish that reminds you why home cooking matters—it's not fancy, but it's made with care and intention, and that translates into every spoonful. I hope it becomes part of your cooking rotation the way it has mine.

Recipes Q&A

→ Can I make this dish vegan?

Yes, replace butter and milk with plant-based alternatives like olive oil and almond milk to keep it fully vegan without compromising flavor.

→ Are gluten-free options available?

Use gluten-free vegetable broth and tamari instead of soy sauce to ensure the dish remains gluten-free.

→ How do I prepare the lentil filling?

Sauté onions, garlic, carrots, and celery before simmering lentils with tomato paste, soy sauce, herbs, and vegetable broth until tender.

→ What is the best way to mash sweet potatoes?

Boil peeled sweet potatoes until soft, then mash with butter (or oil) and milk (or plant milk) until smooth and creamy.

→ Can I add extra vegetables?

Absolutely; chopped mushrooms or bell peppers can be added to the lentil mixture for added flavor and texture.