If using chicken or turkey, lightly spray a skillet with cooking spray. Put ground beef, chicken, or turkey in the skillet; use a wooden spoon to break up the meat. Put the skillet on a burner. Turn the burner to medium-high heat. Cook until no pink color is left in the meat, stirring now and then with the wooden spoon. This will take 6 to 10 minutes. Turn off burner. Remove skillet from burner.
Place a colander over a bowl. Spoon meat into the colander and let the fat drain into the bowl. Put fat in a container to throw away.
Stir 1/2 cup salsa and the oregano into the meat. Cover skillet and put skillet on a burner. Turn the burner to medium heat. Cook for 5 minutes, stirring with the wooden spoon after 3 minutes. Turn off burner. Remove skillet from burner. Put meat in a bowl.
While meat mixture is cooking, tear or cut lettuce into bite-size pieces. Use kitchen scissors to open the package of taco shells.
To make tacos, spoon meat mixture into taco shells. Add lettuce and cheese. Top with sour cream, chopped tomato, and extra salsa, if you like.
Serve with fresh orange sections and a glass of milk.