Heat the oil in a large pan and add the sliced onions. Fry for 4-5 minutes, stirring regularly, before adding the sliced peppers. Turn up the heat slightly to get these going, and reduce to medium again after a few minutes.
Once the onions and peppers have started to soften, add the chopped garlic and fry for another 2-3 minutes.
Next, add the tomato puree and tinned tomatoes, breaking these up with a spoon. Once the tomatoes have broken apart, add in the vegan stock, smoked paprika, and bay leaves. Simmer for 10-15 minutes, stirring occasionally.
After 10-15 minutes, stir in the drained butter beans, thyme, and grated lemon zest. Simmer for a further 10-15 minutes.
With 5 minutes to go, add the spinach leaves and mix these through the stew. It'll look like a lot at first, but these will soon wilt.
Adjust the seasoning to taste, before serving with basmati rice and chopped fresh parsley.