Fill a huge pot with 12 cups water and heat to the point of boiling over high intensity. Set up an ice-water shower; put away. Add 1 tablespoon salt to bubbling water; return to a bubble. Add Swiss chard and cook until relaxed, around 1 moment. Channel and quickly move to ice-water shower; channel once more.
Heat oil in a medium skillet over medium intensity. Add garlic and cook, mixing, for 1 moment. Add Swiss chard, raisins, and 1/2 teaspoon salt; cook, mixing, 2 to 3 minutes.
Add squeezed orange and cook for 15 seconds; season with salt and serve right away.