30 g (1 1/4 oz) sachet Mexican fajita, taco, or chilli con carne spice mix
400 g (13 oz) can kidney beans, drained and rinsed
400 g (13 oz) can black beans, drained and rinsed
400 g (13 oz) can tomatoes
750 ml (1 1/4 pints) boiling water
1 beef or vegetable stock cube
4 tablespoons soured cream
25 g (1 oz) tortilla chips (optional)
Heat the vegetable oil in a large, heavy-based saucepan or casserole, and cook the onion and pepper over a medium-high heat for 4 minutes. Add the garlic and fry for a further 2 minutes, until lightly coloured.
Stir in the spice mix, then add half of the beans, the chopped tomatoes, measured water and stock cube. Stir well, bring to the boil and simmer for 10–12 minutes, until slightly thickened.
Use a hand-held blender to blend the soup until almost smooth, then stir in the remaining beans and heat through. Ladle into 4 deep bowls and serve immediately with a drizzle of soured cream and a scattering of tortilla chips, if desired.