In a large stockpot, bring water and salt to a boil. Add greens and stir to submerge. Boil greens for 12-15 minutes, stirring occasionally for even cooking. When greens are done, drain them in a colander.
Heat oil in a large sauté pan with a lid. Sauté garlic for 30-60 seconds, stirring and watching carefully so it doesnt burn. Add drained greens, 5-spice powder, sugar and soy sauce, stirring well to combine. Stir and sauté greens for another 5 minutes, until moisture is evaporated and flavors are combined.
Note: This makes a great meal served with rice and grilled meat alongside.