Heat 30 ml (2 tbsp) of the lard in a large heavy-based frying pan and saute the onion until it is soft. Add about 225 ml (8 fl oz) 1 cup of the Frijoles (cooked beans).

Mash the beans with the back of a wooden spoon or potato masher, adding more beans and melted lard or oil until all the ingredients are used up and the beans have formed a heavy paste. Use extra lard or oil if necessary.

Tip out on to a warmed platter, piling the mixture up in a roll. Garnish with the cheese. Spike with the tortilla triangles, placing them at intervals along the length of the roll. Serve as a side dish.

Lard is the traditional (and best tasting) fat for the beans but many people prefer to use corn oil. Avoid using olive oil, which is too strongly flavoured and distinctive.