2 eggs
1/2 - 1 tsp. Dijon mustard
Salt
1 1/4 c. olive oil
1-2 tbsp. white wine vinegar
1/2 oz. tarragon

Put egg yolks, mustard and a pinch of salt into bowl and beat with a whisk. When they are well beaten, starting adding oil, pouring it very, very slowly about 1/2 teaspoon at a time. Increase as the oil catches, about 2 tablespoons at a time. When thick, add white wine vinegar and tarragon. Keep cool and revive just before serving.