2 large boneless, skinless chicken breasts (about 1 1/2 pounds)
6 tablespoons olive oil
Salt and pepper
1 large red onion, halved and sliced
Juice from 1 orange
1cup cider vinegar
1 jalapeño, seeded if you like less heat and chopped, or to taste
1/4cup chopped fresh cilantro, for garnish
Instructions
Heat a grill over moderate heat or turn on the broiler and position the rack 4 inches below the heat source. Halve the chicken breasts horizontally to make 2 thin cutlets each. Flatten each by pressing with your hand.
Rub the cutlets with 2 tablespoons oil, sprinkle with salt and pepper, and grill or broil until they begin to firm and turn golden, 2 to 5 minutes. Turn and cook the other side until the center is white or only slightly pink, another 2 to 5 minutes. (The chicken might cook through before it starts to color; be careful not to let it overcook.) Transfer to a cutting board to rest.
Put the remaining 4 tablespoons oil in a large skillet over medium-high heat. When it’s hot, add the onion and sprinkle with salt and pepper. Cook, stirring occasionally, until soft, 3 to 5 minutes. Add the orange juice, vinegar, jalapeño, and 1/4 cup water and bring to a boil, then immediately turn off the heat. Sprinkle with salt and pepper.
Slice the chicken and transfer it to a shallow serving bowl. Pour the vinaigrette over the chicken. Let it marinate for as long as you can, then serve warm or at room temperature, garnished with cilantro.