Preheat oven to 425°F.
Combine 1 cup flour, undissolved yeast and salt in a large bowl. Add very warm water and oil; mix until well blended, about 1 minute. Gradually add enough remaining flour to make a soft dough. Dough should form a ball and will be slightly sticky. Knead** on a floured surface, adding additional flour if necessary, until smooth and elastic, about 4 minutes. Cover and let rest on floured surface while preparing toppings.
Heat a large skillet and cook ground beef until cooked through. Drain, if needed. Add taco seasoning and water according to package directions. Cook according to package directions. Measure 1 cup taco meat for the pizza; refrigerate the remaining taco meat for another use.
Roll dough into 14 x 10-inch rectangle; place on greased baking sheet or 15 x 10-inch rimmed pan OR, pat dough with floured hands, pressing gently to fill greased pan. Form a rim by pinching the edge of the dough; prick surface with fork.
Combine refried beans and 1/4 cup salsa; carefully spread over crust. Top with reserved taco meat and sprinkle with cheese. Bake on lowest oven rack 15 to 18 minutes until center is set and crust is golden brown.
Remove from oven and top with favorite nacho toppings – diced tomatoes, sliced black olives, diced green onions or jalapeno slices. Cut into squares and serve immediately. Serve with sour cream, guacamole or salsa.
*If you don’t have a thermometer, water should feel very warm to the touch.
**To knead the dough, add just enough flour to the dough and your hands to keep the dough from sticking. Flatten dough and fold it toward you. Using the heels of your hands, push the dough away with a rolling motion. Rotate dough a quarter turn and repeat the “fold, push and turn” steps. Keep kneading dough until it is smooth and elastic. Use a little more flour if dough becomes too sticky, always working the flour into the ball of dough.