If the shrimp is frozen, thaw it in the sink under cold running water (see how to defrost shrimp fast). Thaw the green peas in the microwave.

Cut the pineapple into chunks (see how to slice a pineapple for an easy way to do it).

Heat the oil in a large non-stick frying pan over medium-high heat. Add the chopped onion and chopped mushrooms. Cook, stirring periodically, for 5 minutes.

Add bell peppers and pineapple chunks and stir. Cook, stirring periodically, for 4 minutes.

Add shrimp, green peas and minced garlic. Sprinkle with salt and pepper. Stir, so everything is combined. Cook, stirring periodically, for 3 minutes or until the shrimp and green peas are heated through. Add salt to taste is necessary.