Heat the olive oil in a large pot over medium heat. Add the diced onion and cook for 3 minutes until it starts to soften.
Stir in the minced garlic along with the diced red, green, and yellow bell peppers. Cook for another 4 minutes until the peppers begin to soften.
Add the cumin and oregano. Stir for 30 seconds to toast the spices.
Pour in the vegetable broth, diced tomatoes, and rinsed lentils. Add the epazote sprigs. Bring the mixture to a boil.
Reduce the heat to low, cover the pot, and simmer for 25 minutes until the lentils are tender.
Stir in the fresh corn kernels. Simmer uncovered for 5 more minutes.
Remove the epazote sprigs. Taste and add salt and black pepper as needed before serving.