MAKE PICADILLO: In large 14-inch nonstick skillet combine beef, potato, 1 ¼ teaspoon pepper, and 1 teaspoon salt. Cook over medium-high heat until beef and potatoes begin to brown, about 8 minutes, stirring occasionally to break up meat. Stir in onion and bell pepper, and cook until softened, about 6 minutes. Add in garlic and cumin and cook until fragrant, about 30 seconds.
Stir in flour and cook for 1 minute while stirring constantly. Stir in chopped tomato and water and bring to boil. Reduce heat to medium-low and simmer until thickened slightly, about 1 minute. Season with salt and pepper to taste. Remove from heat, and cover to keep warm.
MAKE TACOS: In a large heavy-bottomed skillet heat 1 inch of oil over medium-high heat until oil reaches 350 degrees (the amount of oil will you use vary depending on your pan size). Fry tortillas, one at a time, by folding in half and laying one half flat in oil while holding other half open with tongs. Cook for 30-60 seconds, or until golden and crisp, and then repeat with other half to form a taco shell. Place taco shell on paper towel-lined plate, and repeat with remaining tortillas.
Spoon Picadillo into taco shells and top with tomatoes, lettuce, cheese, avocado, salsa, and chopped cilantro. Serve immediately.
This recipe makes 2 tacos. The serving size is 2 tacos per person.