Heat oven to 425°F. Spray 13x9-inch (3-quart) glass baking dish with cooking spray.
In large skillet, heat oil over medium-high heat. Cook beef in oil 5 to 7 minutes, stirring occasionally, until thoroughly cooked; drain. Stir in 2/3 cup water and the taco seasoning mix. Cook over medium heat 3 to 4 minutes, stirring frequently, until thickened. Remove from heat.
Separate each can of dough into 10 biscuits; flatten each biscuit into thin round. Spoon1 tablespoon beef mixture onto center of each round; top with green pepper and 1 cheese piece. Fold edges up and over filling; pinch to seal. Place biscuits, seam sides down, in baking dish.
In small bowl, beat egg and 1 tablespoon water. Lightly brush tops of biscuits with egg mixture.
Bake 15 to 20 minutes or until golden brown. Serve biscuits warm with salsa.