1 Pound brown or large green lentils, rinsed and picked over
10 cups vegetable broth or water
1 jalapeno pepper, steamed, seeded and chopped
2 teaspoons whole coriander seeds
1 1/2 teaspoons cumin seeds
21/2 teaspoons dried oregano
2 bay leaves
2 medium Yukon gold, russet or red potatoes (1 1/4 pounds), scrubbed and cut into 1/2 inch dice
10 ounces baby spinach, chopped
1 small butternut squash (1 pound), peeled seeded and cut into 1/2 inch dice (about 3 cups)
2 tablespoons olive oil
1 large onion, chopped
2 ribs celery, with leaves, sliced
3 large garlic cloves, finely chopped
2 teaspoons kosher salt, or more to taste
1/2 teaspoon freshly ground pepper, or more to taste
1/3 cup fresh lemon juice
In large soup pot over medium heat, combine the lentils, stock or water, jalapeno, coriander, cumin, oregano, and bay leaves. Bring to boil, then reduce heat to low. Simmer, partially covered, about 30 minutes, until lentils and tender.
Add potatoes, spinach and butternut squash, re-cover and cook another 15 to 20 minutes, until the potatoes and squash are tender.
Meanwhile, in a large skillet over medium heat, heat the olive oil until simmering. Add onion, and cook, stirring, until it starts to soften, 3 to 4 minutes. Add celery and garlic and cook, stirring ofteb, until they soften, 3 minutes. Add the mixture to the soup, de-glazing the skillet with a little soup liquid and adding the de-glazed contents back to the soup pot. Add salt and pepper, taste, and add more if needed. Pick out and discard the bay leaves.
Thinly slice one of the lemons and cut the other into wedges. Just before serving, stir the lemon juice into the soup, Serve the soup hot, with a lemon slice floating atop each bowl. Pass lemon wedges at the table.