Mexican potatoes

INGREDIENTS

• 800g potatoes , cut into cubes
• 1 tbsp olive oil
• 1 onion , finely chopped
• 1 garlic clove , finely chopped
• ½ tsp mild chilli powder
• ½ tsp paprika
• 1 tsp cumin
• ½ tsp cayenne pepper
• soured cream , to serve