How to Make It
Whisk together oyster sauce, fish sauce, and 1 teaspoon oil in a small bowl until combined. If desired, stir in chile and sugar. Add additional oyster sauce, if desired. Stir in 1 1/2 teaspoons garlic; set aside. Whisk together 2 teaspoons water and cornstarch in a small bowl until milky and smooth; set aside.
Heat remaining 1 tablespoon oil in a 5- to 6-quart Dutch oven over high until shimmering. Add remaining 1 tablespoon garlic; cook, stirring constantly, until fragrant, 5 to 10 seconds. Add kale a few handfuls at a time, stirring until wilted before adding next batch, until all greens have wilted and are reduced to about one-third in volume, about 2 minutes and 30 seconds.
Add oyster sauce mixture to kale; stir to fully coat greens. Cook, stirring often, until greens have released most of their liquid, about 40 seconds. Stir in cornstarch mixture; cook, stirring constantly, until sauce thickens slightly and greens take on a silky finish, about 30 seconds. Transfer greens to a platter; garnish with black pepper.