Braised balsamic onions

Cipolline or pearl onions	2 pounds
Butter, unsalted, melted, cooled	2 tablespoons
Salt
Pepper, freshly ground
Wine, dry red	¼ cup
Balsamic vinegar	¼ cup
Sugar	1 teaspoon
Water	1 cup

1. Bring a large pot of salted water to a boil. 
2. Using a paring knife, cut a small X in the stem end of each onion. 
3. Add the onions, and bring to a boil. 
4. Remove from heat, drain, and rinse under cold running water. 
5. Leaving the stem end intact, and using a small, sharp knife, trim off the root end of each onion, and slip off the skin.
   Do not cut too deeply into the onions or they will fall apart.
6. Combine the onions, butter, wine, vinegar, and sugar in a slow cooker. 
7. Season with salt and pepper. 
8. Pour in 1 cup of water. 
9. Set the temperature to LOW, and cook for 20 minutes, stirring occasionally to coat the onions with the butter. Cover, and continue cooking for 2 hours. 
10. Uncover, raise the heat to HIGH, and cook until the liquid has reduced, and the onions are shiny and glazed, about 1 hour. 
11. Season to taste with salt and pepper. 

Recipe from Williams-Sonoma Essentials of Slow Cooking.