Step 1In a medium bowl, whisk together the egg yolks, the vinegar and the mustard until pale yellow. Whisking constantly, add the oil drop by drop at first, until the mixture begins to thicken.
Step 2Still whisking constantly, continue adding the oil, pouring now in a slow stream, until all the oil is incorporated. If the mixture begins to break, you can add a few drops of water to bring it back together. Season with salt to taste. Store, covered, in the refrigerator for up to two days. Makes 1 1/3 cups.
Step 1Remove the crab from the shells. Sprinkle with Meyer lemon juice. Set aside.
Step 2Use a vegetable peeler to peel the celery, then cut it into quarter-inch slices. Trim the radishes and cut them into half-inch dice.
Step 3In a large bowl, combine the crab meat, celery, radishes, chives, chopped celery leaves, mayonnaise and salt and pepper to taste.
Step 4To serve, place two butter lettuce leaves on each of four salad plates. Spoon a quarter of the crab and celery salad atop each. Garnish with a few whole celery leaves.