Preheat oven to 400°F (200°C). Rub each potato with olive oil, sprinkle with salt and pepper, and place on a baking sheet. Bake for 50–60 minutes, until skins are crisp and a knife slides in easily.
In a skillet over medium heat, brown the ground beef for 7–8 minutes. Drain excess fat, then stir in taco seasoning and 1/2 cup water. Simmer for 5 minutes until thick and flavorful.
Let potatoes cool slightly, then slice each one lengthwise. Fluff the insides gently with a fork to create space for the filling.
Spoon the seasoned taco beef evenly into the center of each fluffed potato.
Top with shredded cheddar cheese (let it melt into the meat), then add sour cream, green onions, black olives, diced tomatoes, and jalapeños to taste. Serve warm.