Spicy Wok Shrimp with Coconut Rice

Rinse rice in a sieve under cold water, then shake well to drain and transfer to a 1 1/2-to 2-quart heavy saucepan. Add water (1 1/2 cups), sugar, 1 cup coconut milk, and 3/4 teaspoon salt. Bring to a boil, partially covered, then reduce heat to low and cover completely. Cook 20 minutes, then remove from heat and let stand, covered, 5 minutes.
While rice cooks, trim Broccolini, discarding 1/4 inch from bottom, then cut diagonally into 1-inch lengths. Toss shrimp with Sriracha sauce and remaining 3/4 teaspoon salt in a bowl.
Stir together cornstarch, 1/4 cup chicken broth, and remaining 1/2 cup coconut milk in another bowl until cornstarch is completely dissolved.
Heat a 12- to 14-inch well-seasoned flat-bottomed wok or a 12-inch heavy skillet over high heat until it just begins to smoke, then add oil, swirling to coat. Add Broccolini and stir-fry until bright green, then add remaining 1/4 cup chicken broth and stir-fry until liquid is evaporated, about 3 minutes. Add shrimp mixture and cook, stirring frequently, 2 minutes. Stir cornstarch mixture, then pour it down side of wok and boil, stirring, until sauce is slightly thickened and shrimp are just cooked through, about 3 minutes more. Fluff rice with a fork and serve with shrimp immediately.