Begin by trimming the stems from the Swiss chard and cutting them into bite-sized pieces.
Stack the leaves, slice them lengthwise into strips, and then crosswise into smaller sections.
Rinse both the leaves and stems thoroughly under running water to eliminate any dirt, then pat them dry.
You should have approximately 4 to 6 loosely packed cups of leaves and 1 cup of stems, depending on the size of your chard bunch.
In a large skillet, heat 1 tablespoon of olive oil over medium heat.
Add the chopped red onion and chard stems, sautéing for 3 to 4 minutes until the onion becomes translucent.
Next, incorporate 2 minced garlic cloves, 2 teaspoons of lemon zest, and ¼ teaspoon of kosher salt.
Stir in the chard leaves along with ½ cup of vegetable broth.
Bring the mixture to a boil, then cover the skillet and cook for 3 to 5 minutes, allowing the broth to be absorbed and the leaves to wilt and soften.
Serve warm, with lemon wedges on the side if desired.