Tip the tomatoes, spring onion whites, spices and brown sauce into a saucepan. Bring to a simmer and bubble for 10 mins.
Stir in the beans with some seasoning and heat through for 5 mins. Meanwhile, toast the bread, then chunkily dice half the avocado and mix with a squeeze of lemon or lime juice.
Squash the remaining avocado over one of the pieces of toast, and sandwich with the other. Sit on a plate and top with the hot chilli beans, followed by the diced avocado and a dollop of cooling yogurt. Scatter with the spring onion greens and tuck in.