Heat the olive oil in a large pot over medium heat. Add the onion and cook for 5 minutes until it softens.
Stir in the garlic and ginger. Cook for 1 minute until fragrant.
Add the berbere spice and stir for 30 seconds to toast the spices.
Pour in the lentils, diced tomatoes, and vegetable broth. Bring the mixture to a boil, then reduce to a simmer.
Cover and cook for 25 minutes, stirring occasionally, until the lentils are tender.
Stir in the chopped collard greens and simmer uncovered for 10 more minutes until the greens wilt.
Season with salt to taste. Serve with lemon wedges on the side.