Mustard saffron sauce

. Makes 1 1/2 cups. 6 steps
1 small onion chop finely   Simmer uncovered 5 minutes or until reduced by half
1/2 cup dry white wine
small pinch saffron powder
300ml cream   Simmer uncovered until thickened slightly. Blend or process until smooth
1/3 cup sour cream
1 tablespoon seeded mustard
1 teaspoon chicken stock powder
60g butter chop   Add butter in small pieces, blend until combined
Watch the wine and cream for curdling