Shell the shrimp and butterfly. Place in a bowl and add a teaspoon of salt and a few tablespoons of water. Mix well and set aside 15 to 20 minutes. Then rinse a few times with running water to wash off all the salt. Drain well and set aside.

While shrimp soaks in brine, prepare your favorite rice (white or brown) according to package directions.

While rice is cooking, measure out and prepare other ingredients as indicated. Place onions, shallots and ginger together in a small bowl. Have minced garlic in seperate small bowl, or whole garlic in a garlic press. In another small bowl, mix together curry paste, coriander, curry powder and cumin, until well combined, set aside. In another small bowl, mix together coconut milk, tomato paste, 1 teaspoon of the fish sauce (or to taste) and brown sugar, until well combined, set aside.

If making optional mushrooms: For fresh mushrooms, heat wok or large heavy skillet over high heat, and add 1 tablespoon of oil. When the oil is hot, toss in mushrooms and stir-fry until they begin to change color. Sprinkle in a little fish sauce to salt and cook until mushrooms have just softened. Remove from wok, and reserve. (Note there is no need to precook canned straw mushrooms.)

Lower heat to medium-high and add 1 tablespoon oil. When oil is hot, add onions, shallots and seasoning with salt and pepper to taste, and stir-fry until soft and beginning to brown, about 4 minutes. Add garlic, and stir until fragrant, about 1 minute more. Increase heat to high, add shrimp, and stir-fry for 1 minute. Add the bowl of curry paste, coriander, curry powder and cumin, stirring to coat, until the shrimp are just slightly pink, about 1 to 2 minutes. Stir in the bowl with the coconut cream, tomato paste, fish sauce and brown sugar. Lower heat and simmer for about 5 to 10 minutes until sauce thickens and shrimp are done but not overcooked. If adding mushrooms, only cook shrimp until nearly done. Then, drain the pre-cooked mushrooms from their juices and toss them or the drained, canned straw mushrooms into the wok. Stir well to reheat and mix in with the curry sauce. Transfer to a serving dish and garnish top with a few sprigs of cilantro. Serve hot with plain steamed jasmine rice, and passing lime wedges separately.

*Available at Asian markets and in the Asian foods section of many supermarkets.