Combine the cooked shrimp, tomatoes and avocado in a bowl, season with a little salt and gently toss to combine.
For the vinaigrette, mix together the shallots, Dijon mustard and sherry vinegar. Whisk in olive oil until slightly thickened. Season with sea salt and pepper.
Toss the greens with enough dressing to coat, then top with cooked shrimp, tomato and avocado mixture and add the remaining dressing if necessary.
*You can get sherry vinegar from a store that sells fine vinegar and oils or order it from www.ooliveoil.comYou could also use champagne or red wine vinegar, but it will change the flavor of the salad slightly.