Scrub and pat potatoes dry. Pierce potatoes all over with a fork and bake in the oven, directly on rack, until soft (about 40 to 45 min. depending on the size of your potatoes).
In a bowl, combine all the ingredients for the taco seasoning.
Add the ground beef and onions to the skillet and cook until browned.
Sprinkle the taco seasoning onto the beef, and stir to combine. You may want to add 1 or 2 tbsp. of water if the meat is too dry.
Cook the ground beef another minute or two and set aside.
Slice each potato in half, press the insides down or scoop some out.
Fill the potatoes with the ground beef and top with all the remaining vegetables.