Directions

1Heat a charcoal or gas grill to moderately high heat and put the rack about 4 inches from the flame. Cut the watermelon lengthwise, into halves or quarters, depending on the size of the melon. From each length, cut 11/2-inch-thick slices; remove the rind from each slice. If there are black seeds, use a fork to remove as many of them as you can without beating the flesh up too much.

2 Mix the olive oil with the onion and sprinkle with salt and pepper. Brush or rub the mixture all over the watermelon slices. Grill or broil for about 5 minutes on each side. The flesh should be lightly caramelized and dried out a bit. Sprinkle each slice with cheese, cover the grill and cook just until the cheese melts, about a minute.

3 Serve on buns, toast or hard rolls with the usual burger fixings.