Bring the stock to the boil in a large saucepan. Add the squash, reduce the heat and cover. Simmer gently for about 15 minutes or until the squash is just tender.
Meanwhile, to make the sauce, heat the oil in a frying pan, add the garlic and pepper and fry for 5 minutes, stirring frequently, until very soft. Add the tomatoes, red kidney beans, hot chilli sauce and a little salt and simmer for 5 minutes until pulpy. Set aside.
Drain the squash from the stock, reserving the stock, and return to the pan. Scatter over the spinach leaves, then cover and cook for about 1 minute until the spinach has wilted in the steam.
Pile the vegetables on to servings of rice. Stir 8 tablespoons of the reserved stock into the sauce with the coriander. Spoon over the vegetables and serve with boiled rice.