In a blender or small food processor blend together the garlic paste, the mustard, the lemon juice, the vinegar, and salt and pepper to taste. With the motor running add the oil and blend the mixture until it is combined well. Add the sour cream, 3/4 cup of the cheese, and 2 tablespoons water, or enough to obtain the desired consistency, blend the dressing until it is combined well, and transfer it to a bowl. Stir in the additional cheese. The dressing keeps, covered and chilled, for about 1 week. Makes about 1 1/3 cups. Gourmet September 1991