With the onion I added mushroom and garlic. I also subbed canned diced tomatoes for about a tablespoon of tomato paste and fresh sliced cherry tomatoes. After adding the broth, I added dry basil and oregano and chili flakes. After adding and cooking the lentils (cooked until a little mushy, I added a little more broth to achieve this texture), I added about a quarter cup of Parmesan cheese. It was really good.
