Red Wine Sauce

4 oz  unsalted butter, divided
3 fat shallots, minced
2 garlic cloves minced
1 plum tomato, peeled, seeded and chopped (substitute 1/2 tsp tomato paste)
2 cups red wine such as pinot noir or merlot
1 tbsp. balsamic vinegar and 1/2 tbsp. Hoisen sauce
Kosher salt and freshly ground pepper.

• Put half the butter into sauce pan and heat until foamy.  
• Add the shallots and garlic and sauce briefly, just until glossy and aromatic.   
• Stir in the tomato and saute 2 minutes more. 
• Stir in the wine and raise the heat slightly, bring to a boil, and simmer briefly  until reduced to about 1/2 cup, ten to fifteen minutes.  
• Stir in the vinegar and Hoisen sauce.  
• Pour the sauce through a fine mesh strainer into a clean saucepan and, over low heat whisk in the remaining butter a little bit at a time, whisking until all of the butter is incorporated into the sauce after each addition.  
• Season to taste with a little salt and pepper. Cover and keep warm.

Originally discovered over at the Mrs. Butterfingers blog.