Before you slice the scallops, remove the little side muscle and discard. Place the sliced scallops in a bowl, add about a tablespoon of kosher salt, and mix to make sure all the scallops are salted. Let it rest for a minute or two to quickly cure.
Then, add the zest and juice of the grapefruit. (Use a fork to squeeze out the juice, Let some of the pulp color and flavor the dish.)
Add the juice of 3-4 limes. Make sure you have enough liquid to cover the scallops. Cover the bowl with plastic wrap and stick it in the refrigerator for 1-3 hours.
Remove the scallops from the refrigerator and pour the liquid into a blender or food processor. Add the ginger and blend.
Once the ginger is fully blended into the liquid, pour the liquid back onto the scallops. Now add the onions, cilantro, and habanero. Return to the refridgerator and wait at least ten minutes before serving. This will allow the onions to soften a little with the acidity of the juice.
Taste for seasoning and add more salt, if needed. Serve with totopos (Thick tortilla chips) or tostadas.