Crème fraîche is the closest substitute to Mexico’s sour cream, known as ‘crema’, but I like to use the following combination.
½ cup sour cream
½ cup thick plain yoghurt
1 clove garlic, crushed
finely grated zest 1 lime
1 tablespoon lime juice
sea salt and freshly ground pepper
Whisk the sour cream to remove any lumps then stir in the remaining ingredients and season. Cover and chill until ready to serve. Makes 1 cup