Wash and chop the Swiss chard, separating the stems from the leaves. It’s okay to leave the thinner stems attached to the leaves. Peel and slice the garlic.
Optional: If you want a strong lemon flavor, zest half of the lemon before you cut it in half and reserve the zest. Juice zested lemon half and save other lemon half for another recipe or for lemon water.
Preheat sauté pan over medium high heat. Add oil to pan.
Add the Swiss chard stems, garlic, salt, and pepper to the pan. Cook for about 2 to 3 minutes, stirring frequently so the garlic doesn’t burn.
Add the Swiss chard leaves to the pan and stir. (If you are using an 8-inch sauté pan, add the leaves in batches and stir so they wilt, and you can fit more raw leaves into the pan.) Cook for about 3 to 5 minutes, stirring occasionally so all the leaves wilt evenly. (For an 8-inch sauté pan, cook for about 5 to 8 minutes.)
In the last minute of cooking, add your lemon zest and lemon juice (if using).