Heat oven to 375°F. Spray cookie sheet with cooking spray. Unroll both cans of dough on work surface; press into two 12x8-inch rectangles. Cut into total of 8 rectangles.
In 10-inch skillet, cook beef over medium-high heat 5 to 7 minutes, stirring frequently, until thoroughly cooked. Stir in taco seasoning mix and salsa; simmer 5 minutes. Spoon about 1/4 cup meat mixture in center of 1 dough rectangle. Sprinkle with 2 tablespoons cheese. Fold rectangle over to form triangle; press edges with fork to seal. Place on cookie sheet. Brush with egg; sprinkle with cornmeal. Repeat with remaining dough and filling.
Bake 10 to 15 minutes or until deep golden brown.