Cut avocados in half around the pit. Separate the halves. Pop out pit with spoon, then scoop flesh of avocados into a bowl. Squeeze the juice of a lemon over the avocados. Squeeze the juice with the lemon halves facing cut-side up, allowing the juice to spill down over the sides of the lemon into the bowl. This method keeps the seeds in the lemon and out of the guacamole. Add garlic, jalapeno, tomato, onion and salt to the bowl. Mash and mix the ingredients into a chunky dip using a fork. Serve with blue corn tortilla chips.