Drain the beans and rinse. Fill the empty, clean can with water and pour into a saucepan with the beans. Bring them to the boil to warm through, then take them off the heat.

Meanwhile, in a separate medium frying pan, gently fry the onion and garlic in all but a few tablespoons of the olive oil for 5 mins, then add 2 tsp sea salt flakes, the cumin, chilli flakes and tomatoes. Drain the beans, reserving some of the cooking liquid. Add to the onion mixture and cook over a low heat for 30 mins, stirring often and adding some of the cooking liquid if it looks dry.

Using a potato masher, mash the beans with the remaining olive oil, lemon juice and tahini. The final consistency should be a chunky, soft purée. If it splits slightly, mix in a drop of cold water.