With a zester, remove zest from five limes and set aside for garnish.Squeeze limes through strainer into med bowl. Remove any seeds and add any pulp that was caught to the juice. Add the mustard, and vinegar and whisk to mix. Add the olive oil in a stream, whisking briskly. Pour over salad and serve.
NOTES : I used this on a chicken-pasta salad. The amounts are approximate, but the ratios are about right. Since I usually only make enough for the salad at hand, I have no idea how long it would keep. For an oriental or Mexican type salad I would add chopped cilantro and maybe a touch of ground cumin. This would go well with a Cristianos y Morros (black beans and rice) salad.