Pat the shrimp truly dry with paper towels and season with salt. Dry shrimp sear; wet shrimp boil gray in their own steam.
Toast the cauliflower rice in a dry, wide pan over medium-high heat. Spread it, leave it 3 untouched minutes, stir once, 2 minutes more, until nutty and dry. Season, cover and set aside.
Heat the oil in the same or a second pan until barely smoking. Lay the shrimp in a single layer and leave them 90 seconds, until the undersides pink and crust.
Flip, add the butter and garlic, and cook 60 to 90 seconds more, spooning the garlic butter over, until every shrimp is an opaque C shape.
Kill the heat and squeeze in the juice of one lime, scraping the pan's floor.
Serve over the cauliflower rice, sauce poured over, cilantro scattered, lime wedges alongside.