Heat 1 tablespoon oil in heavy medium saucepan over medium heat. Add curry paste and tomato paste and stir until fragrant, about 3 minutes. Add coconut milk, broth, mushrooms, lime juice, oyster sauce and brown sugar; bring to simmer. Remove from heat. Add cherry tomatoes.
Season sauce to taste with salt and pepper.
Heat 2 tablespoons oil in large nonstick skillet over high heat. Sprinkle hens with salt and pepper. Add hens to skillet and cook until browned, about 4 minutes per side. Transfer hens to 13x9x2-inch glass or ceramic baking dish. Pour sauce over. Baked uncovered until hens are cooked through, about 35 minutes. Transfer hens to shallow serving bowl; tent with foil. Skim fat from sauce. Pour sauce over hens. Garnish with basil and chiles, if desired.