About 1/2 cup lime juice (3 or 4 limes)
1/4 cup sugar
1 tablespoon salt, or to taste
2 tablespoons neutral oil, like canola or grape seed
1/2 teaspoon crushed red chili flakes, or to taste
1 1/2 pounds peeled shrimp, or 3 pounds head-on shrimp, left unpeeled
Minced cilantro for garnish
In a small bowl, combine the lime juice, sugar and salt. Place oil in a 10- or 12-inch skillet, and turn the heat to high. A minute later, add the garlic and chili flakes and cook the garlic until it just begins to brown. Immediately add the lime juice mixture all at once, and cook until it reduces by half, or even more, 3 to 5 minutes. There should be only about 1/4 cup of liquid in the skillet, and it should be syrupy.
Add the shrimp, and cook over high heat. The shrimp will give off liquid of their own and begin to turn pink almost immediately. After about 2 minutes, stir contents of pan. Continue cooking, stirring occasionally until all the shrimp are pink, about 4 minutes total. Taste, adjust seasoning, garnish with cilantro and serve with rice.