Duck Breast with grapes

2 duck breasts , skin removed 1 leek , the white bulb of 1 ounce butter 2 tablespoons grapeseed oil 1/2 teaspoon sugar 2 tablespoons red wine vinegar 3/4 cup[...]

4 pekin duck breasts salt & freshly ground black pepper 4 sprigs fresh thyme 1 garlic clove , crush slightly but unpeeled 1/4-1/2 lb cold unsalted butter ,[...]