Benihana Ginger Sauce

5 ounces sliced onion, rinsed in running water for 15 minutes
2 ounces ginger, peeled and sliced thinly
1 lemon, peeled and chopped, juice squeezed
2 cups soy sauce
1 cup vinegar

Combine all ingredients into a blender and mix well. Stir mixture completely before serving. Ginger sauce may be stored in a plastic or stainless steel container in refrigerator for up to one week.