Preheat oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer). Peel and chop onion and garlic. Fry in hot oil. 1⁄2 Add l water and tomatoes together with the juice. Mash tomatoes, bring to the boil.
Season with salt, pepper, sugar and chili. Rinse beans and corn in a sieve, add and simmer for about 5 minutes.
Spread the chips on a baking tray lined with baking paper. Grate cheese over it. Bake in the oven until the cheese melts. Season the soup to taste and serve with chips.