2 tablespoons vegetable or other light oil, 2 turns of the pan
1/2 red onion, sliced
1 teaspoon mustard seeds
1 1/2 to 2 pounds red or yellow Swiss chard, stems removed and tops coarsely chopped
1/4 cup red wine vinegar
Salt and pepper
Heat a large skillet over high heat. Add extra-virgin olive oil and onion. Sear onion and mustard seeds, 2 minutes. Add greens and toss with tongs in oil. Sear greens 2 to 3 minutes. Add vinegar to the pan. Remove pan from heat and season greens with salt and pepper.