Heat the olive oil in a large pot over medium heat. Add the diced onion and cook until it softens and turns translucent.
Stir in the minced garlic, curry powder, and turmeric. Cook for one minute until the spices smell fragrant.
Add the rinsed lentils, kidney beans, diced tomatoes, and vegetable broth. Stir to combine.
Bring the mixture to a boil, then reduce the heat to a simmer. Cover the pot and cook for 25 minutes, stirring occasionally.
Season with salt and black pepper. Remove the pot from the heat and stir in the lemon juice.
Ladle the soup into bowls and top with chopped cilantro before serving.