Make the fry bread dough: In a large bowl, whisk together flour, baking powder, salt, and sugar. Slowly add warm water, mixing until a soft dough forms. Cover and let rest for 30 minutes.
Shape the dough: Divide dough into 6 equal pieces. On a lightly floured surface, roll each piece into a disk about 1/4-inch thick.
Fry the bread: Heat oil in a deep skillet over medium-high heat. Fry each dough disk for 1–2 minutes per side, until golden brown and puffed. Drain on paper towels.
Prepare taco meat: While bread is resting, cook ground beef with taco seasoning until browned and fully cooked. Heat refried beans.
Assemble tacos: Spread a layer of refried beans over each piece of fry bread. Top with taco meat, cheese, lettuce, avocado, salsa, and sour cream.
Serve: Enjoy warm with your favorite taco toppings.