Preheat oven to 375 degrees F. Place a metal rack on a foil lined baking sheet.
Wash the potatoes, pierce skins with a fork to vent steam. Rub the skins with oil.
Place potatoes on the rack. Bake until potatoes are tender in center, Knife carefully inserted in center to test.
While the potatoes are baking, cook the taco meat. Crumble and brown the ground beef in a medium size saucepan or skillet. Drain the grease. Stir in the water and simmer about 10 minutes, stirring frequently. Remove from the stovetop.
Prepare the toppings. Shred the cheese (block cheese is better to use if possible) Dice the onions. Place salsa in a bowl. Remove the seeds and dice the tomato. USING GLOVES, cut the jalapeno in thin slices. Place sour cream in a bowl or set out squeeze bag. I like to arrange the toppings to fill the potato skins in an assembly line fashion. When the potatoes are baked, remove them from the oven and allow to cool 10-15 minutes before slicing open,
Using a serrated knife, cut the potatoes in half and carefully scoop out the centers. Leave about 1/4 of the potatoes inside.
Assemble the potato skins by filling a third of each skin with cheese. Add about a tablespoon of taco meat. (The amount will depend on the size of the potatoes.) Top with cheese. Return to the oven for about 5-10 minutes to melt the cheese.
Top with onions, salsa, jalapeno slice and sour cream. Arrange on a serving tray. Serve the remaining toppings on the side.