Heat the olive oil in a frying pan over medium heat. Add the onion and cook for 8 to 10 minutes until soft and golden.
Remove about two thirds of the onion. Cook the remaining onion for a few more minutes until deeply golden and crisp, then set aside for topping. Return the softer onion to the pan.
Add garlic, cumin, coriander, paprika and chilli flakes and cook for 30 seconds until fragrant. Add tomatoes, salt and black pepper and simmer for 8 to 10 minutes until rich and slightly reduced.
Stir through the butter beans and cook for 3 to 4 minutes until hot and glossy. Mix the yoghurt with lemon juice and salt, then spread over two shallow bowls.
Spoon the warm beans over the yoghurt and finish with crispy onions, herbs and olive oil. Serve with warm flatbread or toast.
