Heat about 1/4 cup oil in a non stick pan and add the potatoes that have been diced. Season with a little salt and pepper. When the potatoes start to fry, cover the pan and reduce the heat low. When the potatoes are tender, remove the lid and let them lightly brown.
When the potatoes are browned, push them to one side and add the ground beef to the same pan. As the meat browns, flip with a spatula and continue cooking and turning until there is no pink.
When there is no pink, combine the meat and potatoes and continue to cook. Drain any excess fat if desired. Add all of the seasonings and about 1/4 cup water. Cook for about 10 minutes until the water is evaporated. Check for seasoning and adjust.
Dice the tomatoes, chop the lettuce and grate the cheese. Wrap the tortillas in damp paper towels and microwave for about 50 seconds or heat them on a griddle.
Build the tacos with ground beef and potato mixture, top with cheese and lettuce and tomatoes. Serve with your favorite salsa.