This is a not so traditional Cuban dressing but I think the fact we are using limes makes up for that:

1/4 cup The best tasting EVOO you can get your hands on
1-2 tbsp Fresh squeezed lime juice
1 tbsp Fresh minced shallots
1/2 tsp Dijon Mustard
1 tsp Salt (to taste)

Mix all ingredients thoroughly with a whisk or a food processor. Taste. It should be somewhat potent in acidity and salt so adjust accordingly. Let sit at least one hour, overnight is even better. Re-Whisk prior to tossing with your salad in a cold bowl. This scales nicely, just keep the ratio of oil to lime juice at about 3:1