1 shallot, minced
1 cup (250 mL) dry sparkling wine
3 tbsp (45 mL) champagne vinegar or white wine vinegar
1/4 tsp (1 mL) pepper
3/4 cup (175 mL) cold butter, cubed
1 tbsp (15 mL) minced fresh tarragon or chives
In small saucepan, boil shallot,wine, vinegar and pepper until reduced to 2 tbsp (25 mL), about 10 minutes.
Reduce heat to low. Being careful not to boil, whisk in 1 cube of butter at a time just until each is melted. Cover and set aside. (Make-ahead: Set aside for up to 1 hour.
Use at room temperature or rewarm in bowl over saucepan of hot water, whisking often.)
Stir in tarragon. Serve.