In a small heavy saucepan, combine the saffron, shallot, vinegar, and wine. Simmer the mixture until it is reduced to about 2 Tablespoons. Stir in the cream and simmer the mixture, whisking occasionally, until the liquid is reduced to 2 Tablespoons. Season the mixture with salt and pepper. Reduce heat to low, and whisk in the butter, 1 piece at a time, but overlapping slightly to keep the sauce from getting too hot. Remove from heat, from time to time, as the butter is whisked in. Remove from heat and season to taste with salt and pepper. Use with pasta and/or seafoods. Makes about 1 cup. (see Fettuccine with Scallops and Peas, a Gourmet Mag. favorite)