Passata rather than chopped tomatoes, because a smooth soup wants a smooth base and you are not going to break down chunks with a camping burner.
- Oil, dried onion and garlic two minutes.
- Cumin and paprika for twenty seconds only. They scorch fast and a burnt spice base cannot be rescued.
- Passata in, stock cube crumbled over, 350 ml water.
- Drained beans in. Simmer fifteen minutes.
- Crush about a third of the beans against the side of the pan. That is what thickens it without flour.
The crushing step is the whole technique. Whole beans in thin tomato is a disappointing bowl; the same beans with a third of them broken down is soup.
Serves 4.