Lamb à l’Orange

• 1 small onion, very finely chopped
• 1 tablespoon oil
• 1 large orange

Fry the onion gently in the oil until soft but not brown. Grate the orange rind; cut three fine slices from the orange. Trim the pith and reserve for garnish. Squeeze the juice from the remainder of the orange and add to the onion with the orange rind, redcurrant jelly and stock. Bring to the boil, reduce heat and cook stirring for 5 minutes. Blend the mustard, sugar, pepper and cornflour toget