Bring water to boil in large saucepan. Add salt and sprinkle in the polenta, stirring with a wooden spoon. Bring back to boil, lower heat to simmer, cover, and cook for about 15 minutes—lifting the lid every few minutes to give it a stir—until soft textured. Remove from heat, stir in olive oil and/or butter, cover and let sit while you cook the shrimp.

Heat butter in a large frying pan over medium heat for a couple minutes then add the shrimp and toss a couple times. Add the garlic (mashed with salt) and cook until the shrimp just begin to turn pink. Add the green onions or chives, juice from 1/2 lemon, and sriracha. Toss and cook a couple more minutes until shrimp are done—best not to overcook.

On a platter, layer the polenta, cooked shrimp and sauce, then spritz with remaining lemon half, sprinkle with the parsley, salt, and freshly ground black pepper.