Preheat oven to 400 degrees.
Cut the onion crosswise into 3/4-inch-thick slices, and separate into rings.
Use 16 of the largest rings; reserve remaining onion for another use.
Lightly spoon flour into a dry measuring cup; level with a knife.
Combine flour, salt, paprika, and pepper in a medium bowl.
Stir in beer and egg white.
Heat 1 1/2 tbs oil in a large nonstick skillet over medium-high heat.
Dip 5 onion rings in batter, letting excess drip off.
Add onion rings to pan; cook for 2 minutes on each side or until golden.
Place the onion rings on a jelly-roll pan.
Repeat procedure of dipping onion rings in batter and cooking in remaining oil, ending with 6 rings.
Coat the onion rings with cooking spray.
Bake at 400 degrees for 10 minutes or until crisp.
Serve rings with ketchup.
Ready in 40 min.