Melt butter in a large deep skillet or Dutch oven over medium heat.

Add sliced onion and minced garlic; cook for 2 minutes, stirring occasionally, until softened.

Pour in coconut milk, uncooked long-grain white rice, and fish stock or water; stir to combine.

Bring the mixture to a boil, then cover the skillet or Dutch oven.

Reduce heat to low and simmer for 20 minutes, allowing the rice to absorb most of the liquid (some liquid may remain).

Stir in the cleaned shrimp.

Continue to simmer, covered, for an additional 10 minutes, or until the shrimp turn pink and are cooked through.

Remove the skillet from the heat.

Let the dish stand for 5 minutes to allow the flavors to meld.

Stir in the chopped cilantro and lime juice just before serving.