Cut 1/2 pound tomatillos and 1 small red onion crosswise into 1/2-inch-thick slices. In a large bowl, toss the tomatillos, onion, 1 halved and seeded jalapeno chile, 1/4 cup vegetable oil and 1 finely chopped garlic clove; season with salt and refrigerate for 30 minutes. Meanwhile, preheat a grill to high. Grill the tomatillos until charred on one side, about 3 minutes, and grill the onion and jalapeno, turning once, until crisp-tender and slightly charred, about 8 minutes. Finely chop the vegetables and transfer to a bowl. Stir in 1/4 cup coarsely chopped cilantro, 1 tablespoon fresh lime juice and 1 teaspoon each apple cider vinegar and sugar.