HEAT the olive oil in a large pot on a medium flame. Once hot, add the onions, ginger, garlic, and stir-fry until the onions are slightly browned and translucent.
ADD all your spices - cumin, coriander, turmeric, cayenne (if using), salt & pepper. Give everything a good mix and let the spices roast until aromatic, about 2 minutes.
POUR the can of diced tomatoes along with 1 tsp tomato paste and mix well until the spices have infused with the tomatoes.
ADD the coconut milk and vegetable broth to the pot. Simmer for a few minutes.
ADD the butter beans lower the heat to low, cover your pot, and let simmer for about 15 minutes, until the beans have softened, and the curry thickens a bit.
ADD the chopped spinach or kale to the curry and allow the greens to wilt and softens. To finish, add lemon juice and cook for another 5 minutes.
GARNISH with fresh chopped cilantro and serve.