Red Onion Jam

Make this jam while the lamb roasts. Or make it a day ahead and refrigerate; warm it gently before serving.

• 7 Tbs. unsalted butter
• 2 medium-large red onions, halved and thinly sliced crosswise into half moons (about 6 cups)
• 1/2 cup dry white wine
• 6 Tbs. honey
• 3 Tbs. balsamic vinegar
• Sea salt and freshly ground black pepper

Melt the butter in a heavy-based 3- or 4-qt. saucepan over medium heat. Add the onions and cook, stirring ­occasionally, until they're very soft and stringy looking but not brown, 12 to 15 min. (Reduce the heat to ­medium low if they start to brown.) Add the wine and honey, reduce the heat to medium low if you haven't already, and simmer, stirring occasionally, until the mixture is thick and jammy, another 20 to 30 min. Remove from heat and stir in the vinegar; season with salt and pepper to taste.