Heat a couple of tablespoons of vegetable oil over high heat. Add shrimp and toss 2 minutes then add the mushrooms, garlic, ginger, scallions, salt and pepper and cook 3 to 4 minutes more tossing constantly. Stir in curry paste, roasted red pepper and coconut milk and reduce heat to low. Simmer a few minutes then stir in peas to heat through.
In a sauce pot bring chicken stock, butter and the lime zest to a boil. Add couscous and stir. Turn off heat, cover pot and let stand. Add basil and the lime juice to the pot and fluff with a fork.
Serve couscous topped with a layer of chopped lettuce then a few ladles of red curry shrimp. Garnish with chopped peanuts.