For balsamic syrup
3/4 cup balsamic vinegar
1/4 teaspoon minced fresh rosemary
1/8 teaspoon black peppercorns

For chard
1 bunch Swiss chard (1 lb)
1/4 cup chopped red onion
1 teaspoon finely chopped garlic
1 tablespoon olive oil
1/2 teaspoon salt
1/4 teaspoon black pepper
1 tablespoon water

For lamb chops
8 rib lamb chops (1 1/4 lb total), trimmed of all fat
1 teaspoon finely chopped garlic
1/2 teaspoon salt
1/2 teaspoon finely chopped fresh rosemary
1/4 teaspoon black pepper

Make syrup:
Simmer syrup ingredients in a 1- to 1 1/2-quart nonreactive saucepan (see cooks' note, below) over moderate heat until just syrupy and reduced to about 1/4 cup, about 8 minutes. Pour through a sieve into a small bowl, discarding rosemary and peppercorns.

Saut chard:
Cut stems and center ribs from chard, discarding any tough portions, then cut stems and ribs crosswise into 1/4-inch-thick slices. Stack chard leaves and roll into cylinders. Cut cylinders crosswise to make 1-inch-wide strips.

Cook onion and garlic in oil in a 12-inch nonstick skillet over moderate heat, stirring occasionally, until onion begins to soften, about 4 minutes. Add chard stems and ribs, salt, and pepper and cook, stirring occasionally, until stems are just tender, about 6 minutes. Stir in chard leaves and water and cook, stirring occasionally, until tender, about 8 minutes.

Broil chops while chard cooks:
Preheat broiler. Sprinkle chops with garlic, salt, rosemary, and pepper, then broil on a lightly oiled broiler pan, 4 to 5 inches from heat, turning over once, for medium-rare, 6 to 7 minutes total. Serve chops and chard drizzled with balsamic syrup.

Cooks' note:
Stainless steel and enameled cast iron are nonreactive, but avoid pure aluminum and uncoated iron.

Each serving contains about 263 calories and 14 grams fat.