Prep the avocados. Slice each avocado lengthwise around the pit, twist to open, and remove the pit.
Scoop the flesh into a medium bowl.
Mash to your preferred texture. Use a fork or potato masher. Go chunky for texture, or mash until smooth if you like it creamy.
Add lime juice right away. Pour in the lime juice and stir. This adds flavor and helps slow browning.
Stir in onion and cilantro. Fold them in gently so you keep some texture.
Season and taste. Add salt a little at a time and taste after each stir.
If you want a touch more depth, add a pinch of black pepper or cumin.
Let it rest (briefly). If you have a minute or two, let the bowl sit so flavors meld. Then taste again and adjust salt or lime.