Black and Tan Onion Rings

Cut onions into 1/4-inch slices and separate concentric rings. Set aside. Mix flour, salt (optionally), paprika, cayenne pepper, and the pepper flakes. Add stock until mixture takes on a batter consistency. Pour oil into heavy saucepan, wok, or deep fryer to a depth of 2 to 3 inches. Heat to 350F. Preferably with tongs, coat each ring individually until completely covered with batter. In batches, place rings into the oil until batter takes on various shades of medium and dark brown. Remove rings from oil and place on paper towel to absorb the excess oil. Serves about 8.