Blend first 3 ingredients in blender until smooth.
Heat 1 Tbsp. oil in large skillet on medium heat.
Add garlic and onions; cook 5 min. or until tender.
Remove from skillet.
Heat remaining oil in skillet on medium-high heat.
Add shrimp, in 2 batches; cook and stir 3 min. or until pink.
Remove from skillet; cover to keep warm. Return garlic, onions and shrimp to skillet; stir in sauce mixture. Bring to boil; simmer on low heat 3 min. or until heated through.
Spoon over rice; serve topped with onions and sour cream.