Cut the cheese into 12 slices, 1½- by 1½-inch by ¼-inch. Cut 12 (¼-inch thick) tomato slices. Lightly salt and pepper the tomatoes.

In a large pot of simmering salted water, blanch the chard leaves a few at a time for 30 seconds. Pat dry and cool. Trim leaves to an approximate 6-inch square, using the discarded edges to patch any holes. Shave the white center rib so that it doesn't protrude too much. Lay the smooth side of the leaves down, place one piece of fontina in the center of each and top with a tomato slice (fig. 1). Fold all sides of the leaf up over the tomato forming a packet (fig. 2). (They can be stored, covered and refrigerated, up to 24 hours before serving.)

Preheat a grill. Brush packets on both sides with olive oil and place on a hot grill, tomato side down. When chard is lightly marked and soft, turn packet with a spatula and grill until the other side is hot. Total cooking time is 3 to 4 minutes. Serve at once with lemon wedges if desired.

Makes 12 servings.