Place avocado halves, sour cream, cilantro, lime juice, and salt in a sturdy, resealable plastic bag. Seal bag. Knead bag with your hands to combine ingredients. Place in refrigerator until ready to use (up to 8 hours).Advertisement
To serve, arrange chips on a serving platter. Snip a hole in one corner of the bag. Squeeze avocado mixture onto chips. Sprinkle with onions and tomatoes.