How to Make It
Reserve 32 small frisée leaves for garnish. Coarsely chop 1 cup of the frisée; reserve the rest for another use. In a medium bowl, blend the mayonnaise with the lemon juice, mustard and scallion. Fold in the trout and chopped frisée and season with pepper.
Arrange the endive leaves on a platter. Mound 1 tablespoon of the smoked trout salad on each leaf, garnish with the reserved frisée leaves and serve.
If frisée is difficult to find, substitute another bitter green, like escarole. Look for a head of young escarole, chop it very finely and add it to the salad just before serving.