Shrimp

Prepare the dressing at least an hour before serving, to allow flavors to marry.
Bring a generous amount of water to a boil in a saucepan and place a bowl of iced water near the stove. Place the prepared mirliton in a basket or sieve and submerge in the boiling water for about 15 seconds. Remove and plunge into the iced water, to stop the cooking. Spread on absorbent towels to dry briefly, then transfer to a bowl and drizzle with a spoonful of Three-Pepper Vinaigrette.
Toss, and refrigerate until serving time.

Three-Pepper Vinaigrette

In a small bowl, whisk together the egg yolk and 1 tablespoon of the lemon juice until smooth. Begin drizzling in the olive oil very slowly, whisking all the time, until an emulsion begins to form. Alternate adding the oil and vinegar until both are completely mixed in and emulsified. Whisk in the shallot, garlic, basil, pepper and salt. Fold in the diced peppers and taste for seasoning. 
Refrigerate until serving time.

Serve

Peel and devein the shrimp if necessary (if the vein is dark), leaving the tails on. Toss the lettuce with just enough dressing to coat the leaves lightly. Divide the salad among six small plates, placing it in the center, and top with some of the mirliton. Make a circle of shrimp around the salad, using 4 to 6 shrimp. Place a slice or two of avocado between the shrimp. Scatter with some of the red onion rings and a little of the diced pepper.
Pass a small pitcher of Three-Pepper Vinaigrette at the table.