PREPARATION:

1. Using kitchen shears, cut the shells lengthwise down the back of the shrimp. Do not remove the shells from the shrimp. Remove the vein that runs down the back of the shrimp.
2. Using a sharp knife, cut the shrimp meat lengthwise down the back without cutting all the way through the shrimp. Using your fingers, spread the shrimp meat and shells open to butterfly. Cover and refrigerate the shrimp.
3. Whisk the tandoori paste, lemon juice and 1/4 cup/60 g of yogurt in a 13x9x2-inch/33x23x5-cm baking dish to blend. Using a large sharp knife, score the skin of the game hen halves. Sprinkle the hen halves with salt.
4. Add the hen halves to the tandoori marinade and rub the marinade all over the hen halves. Cover and refrigerate the hen halves for 1 hour and 15 minutes.
5. Add the shrimp to the marinade and rub the marinade all over the shrimp. Continue to marinate the hen halves and shrimp for 45 minutes.
6. Preheat the oven to 500°F/260°C.  Line a heavy large baking sheet with foil. Place a wire rack on the baking sheet. Set the hen halves skin side up on the rack. Roast the hen halves until they are almost cooked through, about 20 minutes.
7. Arrange the shrimp on the rack alongside the hen halves and roast until the hen halves and shrimp are cooked through and golden brown, about 10 minutes longer.
8. Meanwhile, stir the cucumber and remaining 1 cup/240 g of yogurt in a bowl. Season the raita to taste with salt and pepper and reserve. Sprinkle the lettuce on a platter. Arrange the hen halves and shrimp atop the lettuce. Garnish with lemon wedges and cilantro sprigs.  Serve with the raita, mango chutney and naan bread.