Arrange an oven rack about 4 inches from the broiler and preheat broiler.
Melt the butter in a small saucepan with the grapefruit zest and juice and simmer for a couple of minutes. ¬†Oil a large baking sheet. ¬†Sprinkle the fish all over with salt and pepper, including inside the cavities. ¬†Put the fish in a single layer on the baking sheet, then stuff the cavities with some of the couscous. ¬†Drizzle the fish with some of the grapefruit butter and broil, without turning, until the skin blisters and the fish is cooked through but still transluscent at the bone, 12 to 15 minutes.
Baste the fish a couple of times with the remaining grapefruit butter as it broils. ¬†Serve fish with the remaining couscous and grapefruit wedges.
GREEN OLIVE COUSCOUS
Bring a large pot of salted water to a boil for the beans. ¬†Fill a large bowl with ice water and add salt to it until it tastes lightly salty ‚Äď this is to refresh your beans. ¬†When the water comes to a boil add the beans and cook until just tender about 3 minutes. ¬†Drain and then refresh in the salted ice water. ¬†Drain and cut into ¬Ĺ-inch pieces.
Meanwhile, pour cold water over the couscous in a medium bowl (using cold water reserves the couscous‚Äô grainy, nutty texture). ¬†Cover and let stand for 15 minutes. ¬†Combine the vinegar, oil and fennel in a large bowl, season with salt and pepper and stir. ¬†Fold in the couscous along with the pinenuts, green beans and olives. ¬†Season to taste with salt and pepper and finish with a drizzle of olive oil.
Edited: October 2nd, 2009