Heat 1/4 cup vegetable oil in a large nonstick skillet over medium-high heat. Add 4 halved heads endive cut-side down; season with salt. Cook until browned and softened, turning once, about 10 minutes. Add 2 tablespoons white wine vinegar, 1 tablespoon water, 1 teaspoon sugar and a pinch of salt. Simmer, turning to coat, until syrupy, about 30 seconds. Sprinkle with chives.