Makes around 1 ΒΌ quarts
This is pretty spicy; leave out either the habanero or Serrano peppers for a lower spice version. Use one Serrano pepper for a mild version, or a single jalapeno if you're scared of capsaicin. You want at least a little pepper for flavor.
Don't worry about being too precise here.
I am lazy, and usually quarter and then pulse the tomatoes and onions (separately) in a food processor a few times (until the bits are evenly sized). When using a food processor for the tomatoes, after straining they can be wrapped in paper towels (or clean cheese cloth) and squeezed gently to remove some of the liquid (otherwise it separates after a night in the fridge — if you're going to use the guacamole immediately it's OK to skip squeezing the tomatoes).
Make sure to macerate or very finely mince the peppers and garlic (a food chopper works great); otherwise some bits will burn like Hell, and other will not be hot at all. I like a blend of habanero and Serrano; I find the habanero gives an upfront kick that fades quickly, with the Serrano slowly warming in the background to support it.
As for the salt you can use a bit more if you'd prefer. I don't like my guacamole very salty so I use a single teaspoon of fine grained sea salt, but two isn't necessarily overpowering.
I don't use cilantro because I'm indifferent to it and at least one person I know that shares the guacamole actively dislikes it. The lime has been increased a bit to make up for it. A few tablespoons of freshly chopped Italian flat parsley can be incorporated to add a mild herbaceous/bitter note, but trying it both ways I don't feel the need to add any nowadays.