1Melt the butter in a heavy saucepan over medium heat. Add the onions and cook until translucent but not browned, 3 to 4 minutes. Add the cherries and cook until soft, about 2 minutes.
2Add the beer and increase the heat to high. Let the beer simmer briskly until the liquid is reduced by about half, 4 to 6 minutes. Reduce the heat to medium and add the bbq sauce, vinegar, brown sugar, honey, cherry preserves, worcestershire sauce, and a little salt and pepper. Let the sauce simmer gently until slightly thickened, 4 to 6 minutes.
3Remove the pan from the heat, and let the sauce cool slightly, then puree it in a blender. Taste for seasoning, adding more brown sugar, salt and pepper, or any other ingredient as necessary. The sauce should be highly seasoned. Let the sauce cool to room temperature before serving. The sauce can be refrigerated for a week. Return to room temperature before serving.