Heat pressure cooker over medium heat; cook chicken until browned, 2 to 3 minutes per side. Season with paprika, salt, and black pepper.

Combine onion, chili sauce, water, and vinegar in a bowl; pour over chicken.

Close cooker securely and place pressure regulator over vent according to the manufacturer’s instructions. Heat until steam escapes in a steady flow and makes a whistling sound, adjusting temperature until regulator is gently rocking; cook 15 minutes. Remove from heat and let pressure release naturally according to the manufacturer’s instructions, 5 to 10 minutes. Unlock lid and remove.