Heat oil in a large skillet over medium heat. Add ground beef and cook until browned, breaking up meat with a wooden spoon, about 10 minutes. Add onions and sweet potato and cook until soft, about 5 minutes more. Stir in tomato sauce, adobo, garlic, oregano and black pepper. Lower heat to medium-low and simmer until mixture thickens, about 15 minutes.
On a lightly floured work surface, using a rolling pin, roll out discos until 1/2-inch larger in diameter. Spoon about 1 tbsp. meat mixture into middle, fold in half to form a half moon; moisten edges with water and pinch to seal closed, or seal with a fork.
Place a silpat or parchment paper on cookie sheet. Lightly brush with oil. Place formed empanadas on sheet and cook for 15 or until lightly browned. I checked them and turned them over for another 5 minutes. Frying was not needed!