In a large pot or Dutch oven, heat the olive oil over medium heat. Add the diced onion and saute until soft and slightly translucent.
Add the garlic, carrot, and celery and saute for a couple of more minutes.
Stir in the lentils, vegetable broth, water, tomato paste, and bay leaf. Bring to a simmer, then reduce the heat to low.
Simmer until the lentils are soft, stirring occasionally, at least 20 minutes, or up to 30 to 40 minutes, depending on your texture preference. Remove the bay leaf, taste the soup, and add salt and pepper, as needed.
To serve, top each bowl with a drizzle of olive oil and red wine vinegar, if desired.
Nutrition Facts are an estimation and do not include the optional olive oil and red wine vinegar for drizzling on top.Tips:
Be sure to wait to season with salt until after the soup is finished cooking. Otherwise, the lentils may become tough or take longer to become tender.
Lentils to do not require soaking. But rinse them well in cold water to remove any dust or debris.
This soup is very thick like a stew. If you prefer a thinner soup, add an additional 1 to 2 cups of liquid.
Dry lentils: For this recipe, choose green or brown lentils. Red lentils cook much quicker, are softer, and don't hold their texture. Save them for recipes such as Red Lentil Potato Soup.
Red onion: I prefer red onion in this recipe, but sweeter white onion works well, too.
Carrots and celery: Don't have them? Or don't care for them? Simply leave them out.
Red wine vinegar: I recommend drizzling a little red wine vinegar over each bowl of soup when serving. But you can use a squeeze of fresh lemon juice instead.
Instant Pot cooking instructions:Use the Saute function to saute the onion, garlic, carrot and celery. Then add the lentils, broth, water, tomato paste, and bay leaf and lock the lid. Pressure Cook on high for 7 minutes. Allow the pressure to release naturally, then season to taste with salt and pepper.Storing and freezing:Leftover soup can be covered and refrigerated for 3-4 days or frozen for up to 3 months. I like to freeze servings in individual portions in mason jars or small glass containers with lids. Be sure to allow a little room at the top since the liquid will expand when frozen.To reheat, first defrost the frozen container of soup in the refrigerator overnight. It will be thicker, so you may want to add a little water before reheating it in a pot on the stove or in a microwave-safe bowl.For tips on freezing, refer to USDA Freezing and Food Safety.