Cut the kale and chard into 1" strips, removing the largest parts of the kale stalk. Dice the onion (in whatever shape/size you like).

Sauté the onion over medium heat in the olive oil, until it begins to sweat, about 2 minutes. Add the leafy greens, and cook another four or five minutes, until the leaves have softened and cooked down. Stir in the hot sauce and pepper.