In large shallow bowl, combine the lemon juice, garlic, 1 tablespoon of the oil, cilantro, cayenne, turmeric, and salt(Keep in mind that some shrimp are sold frozen with salt already added to them so if you're using frozen instead of fresh, please be careful with the amount of salt you add.) Stir well and taste...the marinade should be tangy and a lil spicy. Add the shrimp and toss to coat evenly with the marinade.