Why You’ll Love This Recipe

Fully plant-based: Perfect for vegans and anyone avoiding dairy or animal products.
Flavor-packed: Sautéing the vegetables brings out their natural sweetness and umami depth.
Simple ingredients: Made with pantry staples like potatoes, leeks, and vegetable broth.
Comforting and creamy: The oat milk and potato starch create a silky, rich texture.

ingredients

(Tip: You’ll find the full list of ingredients and measurements in the recipe card below.)

¼ cup vegan butter
3 tablespoons olive oil
2 large leeks, diced
1 yellow onion, minced
1 large carrot, diced
1 cup minced oyster mushrooms (Pleurotus)
2 pounds potatoes, peeled and diced
4 cups low-sodium vegetable broth
1 cup unsweetened oat milk, divided
1 tablespoon potato starch
Salt and ground black pepper, to taste

directions

Turn on the Sauté function of your slow cooker.
Heat vegan butter and olive oil, then add leeks, onion, carrot, and mushrooms.
Sauté for about 7 minutes, until vegetables are softened and mushrooms have released their liquid.
Add the diced potatoes and vegetable broth; mix well.
Create a slurry by mixing 1 tablespoon of oat milk with the potato starch, and stir it into the soup.
Heat the remaining oat milk separately in the microwave (~30 seconds), then add it to the slow cooker.
Season with salt and pepper. Turn off the Sauté function.
Cook on Low for 6 hours or High for 3½ hours.
Stir before serving.

Servings and timing

Servings: 8
Prep time: 20 minutes
Cook time: 3 hours 40 minutes
Total time: 4 hours

Variations

Add herbs: Stir in thyme, rosemary, or bay leaf for an herbal boost.
Creamier texture: Blend half the soup before serving for a thicker consistency.
Protein boost: Add cooked white beans or lentils at the end for more protein.
Spicy version: Add a pinch of chili flakes or cayenne for heat.

storage/reheating

Storage: Refrigerate leftovers in an airtight container for up to 5 days.
Freezing: This soup freezes well for up to 3 months. Thaw overnight in the fridge before reheating.
Reheating: Warm gently on the stovetop or in the microwave, stirring occasionally.

FAQs

1. Can I use other plant-based milks instead of oat milk?

Yes, but use only unsweetened and neutral-flavored varieties. Avoid rice milk; flax or soy milk are better alternatives.

2. Is it necessary to sauté the vegetables first?

Yes—sautéing builds flavor and helps achieve a deep, rich soup base.

3. Can I skip the mushrooms?

Yes, but they add a savory umami depth. You can replace them with extra carrots or celery if preferred.

4. How can I thicken the soup more?

Blend part of the soup or add more potato starch slurry for a thicker texture.

5. What kind of potatoes are best for this recipe?

Starchy varieties like Russets or Yukon Gold work best for creaminess.

6. Can I add greens like spinach or kale?

Absolutely—stir them in during the last 30 minutes of cooking.

7. What if I don’t have a sauté function on my slow cooker?

Use a skillet on the stove to sauté the vegetables, then transfer to your slow cooker.

8. How can I add more protein?

Mix in canned chickpeas or cooked lentils toward the end of cooking.

9. Can I make this in an Instant Pot?

Yes, use the sauté mode for prep and pressure cook on high for about 8 minutes, then quick release.

10. Is this soup gluten-free?

Yes, as long as your vegetable broth and oat milk are certified gluten-free.

Conclusion

This Slow Cooker Vegan Leek and Potato Soup proves that comfort food doesn’t need meat or dairy to be deeply satisfying. It’s an easy, nourishing option for any day of the week, with rich flavors, wholesome ingredients, and versatile serving options. Whether you’re vegan or just trying to eat more plant-based meals, this soup will warm you from the inside out.

Slow Cooker Vegan Leek and Potato Soup