Harvest nopales pads with a sharp knife, slicing them away from the plant close to the ground. Select bright green pads no larger than your hand, pinching them gently to make sure they're firm but not too hard or very squishy. Wear rubber gloves for harvest, and place the pads in a bowl.
Hold each pad under cool running water, still wearing your rubber gloves. Scrub each pad with a sponge. First, rub the sponge over the pads to remove dirt and loose prickly hairs. Then scrub a little harder to remove the rest of the hairs and the green nodes that surround them. They should snap off easily.
Rinse each pad thoroughly before placing it into a clean bowl. Slice the pads lengthwise with a clean knife, turn them, and slice them through widthwise into pieces about ½-inch square.
Fill your juicer with cactus cubes. Pulse it until the pieces are mush, then run it on high until the pieces are liquefied. Pour into a tall glass and sweeten with honey or agave nectar. It's also tasty with ice.
Rinse your gloves, harvesting bowl and harvesting knife thoroughly before placing them aside to be washed by hand or in the dishwasher. Spray out the sink thoroughly, also, running as many of the little hairs down the drain as possible.