Heat 3 tablespoons vegetable oil or unsalted butter in a wok or large nonstick frying pan over medium-high heat until shimmering or melted. Add 4 cups leftover cooked white rice and sprinkle with 1/4 cup fried garlic, 1 teaspoon MSG, and 1/4 teaspoon kosher salt. Fry, tossing often, until heated through and fragrant, about 5 minutes. Taste and season with more kosher salt as needed. Transfer to a serving bowl and cover to keep warm.