Fill a large stockpot about ¾ full with water and 1-2 teaspoon/s salt and heat on high to a full boil. While the water is heating, slice peppers in half. Carefully cut out stems and remove all seeds. Once water is boiling, use tongs to drop pepper halves in the pot; cook for about 5 minutes. Depending on the size of your pot, you may have to boil the peppers in two batches. Remove pepper halves with tongs and transfer to a large colander in the sink; invert halves so excess water can drain.

Brown ground beef or turkey in a large skillet, seasoning with salt and pepper to taste. Drain excess grease. Stir in rice, salsa, seasoning packet and feta cheese.

Spray two 9×13-inch baking dishes with nonstick spray, and arrange pepper halves, cut side up. Spoon beef and rice mixture into peppers—Bake at 375 degrees for 20 minutes. Remove peppers from the oven and sprinkle tops with shredded cheddar cheese; bake for additional 5 minutes or until cheese is melted.