This is a wonderful and easy appetizer. If you want to serve this on a buffet where it will be out for more than an hour, put ice in a pretty bowl and place the bowl of shrimp into the ice-filled bowl. If you do this you won't have to worry about shrimp spoilage or food poisoning--never a good thing at a party. Refill your bowl of ice halfway through the party.
1/4 c. tarragon flavored vinegar
1/4 c. red wine vinegar
1 tsp. freshly ground black pepper
1/4 c. Coleman's dry mustard (don't even try to substitute some other brand)
2 tsp. Hot Red Pepper flakes
2 tsp. salt
1/2 c. vegetable oil
1/4 c. minced parsley
6 green onions, chopped
2 - 1/2 lbs. med to large shrimp, cooked, peeled and deveined; tails on.
In a 3 quart bow, whisk together vinegars, black pepper, mustard, pepper flakes and salt. While whisking, slowly pour in oil until slightly thickened. Stir in parsley and green onions. Set sauce aside. Drain cooked shrimp in colander and shake to remove excess water. Immediately stir shrimp into sauce, cover and refrigerate overnight or for up to 2 days. Spoon into glass serving bowl. Serve with cocktail forks or sturdy toothpicks.
[You can save time by ordering precooked, peeled and deveined shrimp]