Red Chard and Carmalized Onions

I've never cooked red chard until recently and boy am I glad I did. This was easy and delicious!

RED CHARD AND CARMALIZED ONIONS

1 large yellow onion, chopped
2 tablespoons olive oil
1 teaspoon brown sugar
1 bunch red Swiss chard, rinsed and chopped
1/4 cup kalamata olives
2 tablespoons capers
1/2 teaspoon coarse sea salt, or to taste
freshly ground black pepper to taste
1 lemon, juiced

In a cast iron skillet, cook onions in olive oil over medium-high heat until they begin to brown. Stir in brown sugar, and continue cooking for a few minutes. When onions are brown and tender, stir in chard and olives. Cook until chard is slightly wilted. Stir in capers and salt, and continue cooking until chard is completely wilted, about 3 minutes. Season with black pepper and squeeze lemon over the top.