2 Tbsp olive oil
1 onion, diced
1 red bell pepper, diced
1-1/2 cups brown lentils
1 Tbsp Greek seasoning
1 Tbsp fresh thyme leaves, or 1/2 Tbsp dried thyme leaves
1 Tbsp tomato paste
7-8 cups chicken stock, homemade or low-sodium store-bought
Zest of 1 lemon
3-4 Tbsp crumbled feta cheese (I use fat-free feta), to taste
Kosher salt and fresh black pepper, to taste
In a 5-quart Dutch oven or heavy stock pot, heat the oil over low heat. Add the onions and red pepper, and cook for 3-4 minutes, until the onions are translucent and just beginning to brown. Stir in the lentils, Greek seasoning, thyme and tomato paste. Then, add 7 cups of the stock, reserving one cup.
Increase the heat to high, and bring the soup to a boil. Then, reduce heat to simmer, cover the pot, and cook, stirring every 15 minutes, for 1 hour.
If the lentils are not yet soft and too much liquid has been absorbed to allow them to finish cooking, add the remaining 1 cup of chicken stock. Also, at this time stir in the lemon zest and feta. Taste, and season with kosher salt and lots of fresh black pepper.
Cover the pot, and continue cooking for 15 minutes, or until the lentils are soft but not completely mushy.
Serve hot, with additional crumbled feta on the side. Or, allow the soup to cool completely, then refrigerate in air-tight containers, or freeze.