Sprinkle some salt on the ¼ small red onion and use a squeezing motion with your hand to coax out some liquid. Rinse them with cold water, then pass them through a sieve and use a paper towel to remove as much water as possible.
Add the onions to a bowl. Roughly crumble the 1 grapefruit segments removing any remaining membranes into the bowl. It's okay if some juice comes out of the grapefruit.
Add the 2 avocados, 2 tablespoons cilantro, hot sauce and 1 teaspoon salt, then stir to mash up the avocado a bit, but leave some chunks. Serve with tortilla chips.