Add chopped onion and jalapeno to mortar and mash. Add salt and mash until a bit of water is released.
Add the pitted avocados and mash it using the pestle. Combine everything. Add the cilantro and mix it in. You can leave it chunky or mash until it is creamy.
Start with 2 tsp of lime. Use a spoon to mix it in. Add more if you need to. Check salt and add more if needed. Transfer to a serving bowl.
Alternatively, crush the onion and jalapeno using a fork on a cutting board. Transfer to a bowl. Add salt. Mash in the avocados. Add cilantro and lime juice. Mash everything together using the fork.
Serve with corn chips.