Heat the olive oil in a large pot over medium heat. Add the diced onion and cook until it softens, about 5 minutes.
Stir in the minced garlic, curry powder, and cumin. Cook for 1 minute until the spices smell fragrant.
Add the rinsed lentils and vegetable broth. Bring the mixture to a boil, then reduce heat to low and simmer for 15 minutes.
Add the cauliflower florets to the pot. Continue simmering for another 15 minutes until the lentils and cauliflower are tender.
Stir in the frozen peas and cook for 3 more minutes until the peas are heated through.
Season with salt and black pepper to taste. Ladle the stew into bowls and top with chopped cilantro before serving.