This is more of a "method" than a recipe. I learned how to sauté chard (as well as many other things) from Alice Waters’ The Art of Simple Food. This is, indeed the simplest way of cooking chard, but it is also so easy and delicious that I rarely serve it any other way.
Rainbow Swiss chard, the kind Native Son grows, is my favorite because of its striking colors, and prepared this way—with stems in—you get to keep some of those beautiful hues on your plate, making the chard (rather than the salmon), the highlight of the meal.
For added flavor, toss in a little minced garlic and a squeeze of fresh lemon to the pan before sautéing the leaves. Or try minced ginger and a freshly squeezed orange. Other great additions include Parmesan cheese, red pepper flakes, and soy sauce—just not all together!
Your imagination is really the limit when it comes to chard. I've enjoyed it in soups, stews, and quiches, basically anywhere you might use kale. It also makes a nice warm salad. Check out this great overview of recipes using Swiss chard.
Simple Sautéed Swiss Chard
Wash one large bunch of chard. Peel the leaves apart from the stems. Trim the edges of the stems, making a stack of little spears. Dice the stems as you would celery, set aside. Cut the leaves into 2-inch "ribbons," set aside.
Heat a couple of tablespoons of oil in a heavy skillet. Add one small onion, diced fine. Sauté until tender, about five minutes. Add the diced chard stems, and sauté another three minutes. When onion and stems are tender, but not mushy, add the chard leaves, tossing and coating with the oil. Sauté until the leaves have just begun to wilt and turn dark green, taking care not to let them get overcooked (stringy and mushy). Remove from the pan, season with salt, and serve immediately.