Caramelized Red Onion Relish

Ingredients
- 8 Tbs. (1 stick) unsalted butter
- 8 lb. red onions (about 10 large), halved and thinly sliced
- 2 tsp. salt, plus more, to taste
- 1⁄3 cup firmly packed light brown sugar
- 1⁄3 cup crème de cassis
- 1⁄3 cup red wine vinegar
- 1 Tbs. minced fresh thyme or 1 1⁄2 tsp. dried
- Freshly ground pepper, to taste
Directions
In a very large fry pan over medium heat, melt 4 Tbs. (1/2 stick) of the butter. Add half of the onions and 1 tsp. of the salt. Cover and cook, stirring occasionally, until the onions are tender and have rendered some of their liquid, about 15 minutes. Transfer to a bowl. Repeat with the remaining 4 Tbs. (1/2 stick) butter, the remaining onions and the remaining 1 tsp. salt.Return the first batch of onions and any juices from their bowl to the fry pan. Stir in the brown sugar and cassis, and then add the vinegar. Cook over low heat, stirring and tossing frequently, until the onion juices have evaporated, about 30 minutes. Continue to cook, uncovered, stirring occasionally, until the onions are tender and lightly browned, 20 to 30 minutes more.
Stir in the thyme and season with pepper. Taste and adjust the seasonings with salt. Serve hot. Serves 8 to 10.
Make-Ahead Tip: The relish can be prepared up to 3 days in advance. Let cool, cover and refrigerate, then rewarm it over low heat just before serving.