Peel the stalk of the broccoli, remove the florets and cut into 1-inch pieces. Cut the stalk in half crosswise and then slice each half into 1/8-inch thick slices lengthwise. Place the stalk pieces in the bottom of a 2 1/2 to 3-quart saucepan, add the water and salt. Lay the florets on top. Cover, place over high heat and cook for 3 minutes. Decrease the heat to low and cook for an additional 3 minutes. Remove from the heat, add the butter and stir to combine. Serve immediately.