Put the onion, cilantro, lime juice, olive oil, garlic, and jalapeno pepper sauce into a food processor and chop finely, but don't let it become a slush. Put this into a plastic or china bowl.
Chop the tomatoes coarsely and add to the bowl. Add the salt and ketchup.
Cut the avocados in half. Remove the pits. With a spoon, scoop out the flesh into the bowl, avoiding any discolored or stringy parts.
With a large wire whisk, mash and mix everything together. The guacamole should be on the chunky side, not a puree. Add salt and more Tabasco to taste. Serve with tortilla chips.
