I found it here but it's a recipe I'd used before and lost. I used to eat it over pasta or rice but lately I just eat it plain like a stew, which is also good. I'm adjusting it to what I've actually been doing:
1 bag (16oz) dried lentils
oil
3/4 cup chopped onion (or more)
5 cloves garlic, minced
1/2 teaspoon red pepper flakes (or to taste)
1/2 teaspoon black pepper (or to taste)
1 28oz can crushed tomatoes
1 (6 ounce) can tomato paste
1 tablespoon white vinegar
2 bouillon cubes
1/2 teaspoon dried whole basil (or more)
1/2 teaspoon dried whole oregano (or more)
**I do not add any salt while cooking and rarely end up needing it, because most bouillon and most canned tomatoes have salt.
Sort/pick over lentils to remove any debris or stones. Rinse them if you're feeling ambitious. Put them in a 3 quart pot with a few extra inches of water, bring to a boil, turn down to a simmer, put lid on, cook til soft-ish (anywhere from 20 to 40 minutes.) If they're getting dry add more water. It's not rocket science but I try not to end up with a huge amount of water when they're done, just enough that they stay covered.
Meanwhile: Chop onions and garlic. Put a few tsp of oil in a heavy pot (mine is 4 1/2 quarts), turn on heat to medium, let it heat up. Add onion and garlic and red pepper and oregano; saute until tender. Add tomatoes, vinegar, and bouillon and simmer over low heat. Once lentils are mostly soft, dump them into the pot, add dried basil, stir well, and let it cook on a very low flame for a bit to help the flavors meld. (It can burn/stick more easily at this stage so watch out.) This tends to taste better after it's sat for a few hours or the next day - it's good as leftovers and good to freeze.