Sauce
1 tablespoon olive oil
2 cups chopped onions
3 ½ cups coarsely chopped seeded plum tomatoes (about 2 pounds)
¼ cup dry white wine
2 ½ teaspoons ground cumin
1 cup pareve whipping cream

Mix first 6 ingredients in medium bowl. Place hens in 15x10x2-inch glass baking dish. Pour mixture over hens. Cover, chill overnight.
Preheat oven to 400°F. Transfer hens to heavy baking pan. Sprinkle inside and outside of hens with salt and pepper. Pour marinade over. Bake until cooked through, basting occasionally with juices about 1 hour 10 minutes.

Meanwhile, prepare sauce: heat oil in heavy medium saucepan over medium-high heat. Add onions and sauté until golden, about 6 minutes. Add tomatoes, wine and cumin; sauté until tomatoes are tender, about 10 minutes. Purée mixture in blender; return to sauce pan. Add pareve cream and simmer until slightly thickened, about 5 minutes. Season with salt and pepper. Keep warm.