My brother and his wife made this for a birthday party recently. It's great as a dip, but also makes a delicious wrap. When I made it myself I ended up using three avocados, adding each one fresh to the portion we were ready to eat.
Pico De Gallo
1 purple onion, diced (I used less - maybe 1/3 of an onion - as we're not huge fans of purple onions)
4 plum tomatoes, diced
1 jalapeno, diced finely
1 bell pepper, diced
Juice of 2 limes
Handful of chopped cilantro
Mix together everything but the avocado and refrigerate overnight. Add avocado when serving.