1 Prepare the chard leaves. Leaf by leaf, cut out the tough center stem. Slice the stems crosswise in 1/4-inch to 1/2-inch pieces. Keep separate from the leaves. Slice the leaves crosswise into 1-inch thick strips.
2 Heat oil in a large, wide, stick-free saut? pan on medium high heat. Add the chopped chard stems, the shallots or onions, and the mustard seeds. Sprinkle a little salt over the chard. Saut? until the onions or shallots become translucent. About this time some of the mustard seeds may start to make a popping noise. Add the chard leaf greens. Sprinkle on a little more salt and toss to coat with the oil and onion mixture.
3 Reduce the heat to low and cover the pan. Let cook for a couple minutes only, lifting up the pan cover to turn the greens over in the pan after the first minute. The greens should cook down considerably. When they are just wilted, remove from heat and place in a serving bowl. Sprinkle on seasoned rice vinegar right before serving.
Serves 2-3.