@izzythepush,
Onion? This california girl (avocado tree in my aunt's backyard) makes simple guacamole, as did my latina friends: avocado, salt, maybe a small squeeze of lemon, and that's it. I like spices and onions and garlic, but they go into other stuff. One friend did do guac with fresh crab and some sherry type bottled dressing, but that was unusual.
The key is a great Haas avocado.