In small bowl, mix salt, paprika, pepper and oil to form paste; spread evenly over each piece of chicken.
In 5- to 6-quart slow cooker, place onion slices. Arrange chicken over onion. Separate garlic into cloves; do not peel cloves. Place garlic cloves around chicken.
Cover; cook on Low setting 7 to 8 hours.
With slotted spoon, remove chicken, onion and garlic from slow cooker; place on serving platter. Squeeze garlic cloves to use cooked garlic on mashed potatoes, vegetables or bread.