In a shallow dish, combine the marinade ingredients. Add the squab and turn to coat. Cover and marinate overnight in the refrigerator or for 3 hours at room temperature.

Preheat the grill or broiler.

Place the squab skin side down on the hottest part of the grill. Sprinkle with salt and pepper, Cook until the breast meat nearest the bone is medium to medium rare, 8 to 10 minutes on the first side and 4 to 5 minutes when turned over.

In a 12- to 14-inch skillet, sauté the onion in the olive oil until softened, 8 to 10 minutes. Add the lemon juice and zest and the kale and toss until wilted, 3 to 4 minutes. Season with salt and pepper and pile in the center of a serving platter. Arrange the squab over the greens, pour 3 tablespoons of pomegranate molasses over each bird, and serve immediately.