How to Make It
In a small skillet, toast the fennel seeds over moderate heat until fragrant, about 40 seconds. Transfer the seeds to a mortar to cool, then pound to a coarse powder. In a small bowl, cover the ground fennel with 2 tablespoons of the grapeseed oil and let stand until flavorful, at least 30 minutes. Strain the fennel oil.
Thinly slice the fennel on a mandoline. Spread the fennel in a large, wide baking dish in an even layer. Pour the grapefruit, orange and lime juices plus 1/4 cup of the lemon juice over the fennel and refrigerate for 1 1/2 hours.
Drain the citrus juices into a medium saucepan and boil over high heat until reduced to 1/2 cup, about 20 minutes. Pour the juice into a bowl set in ice water and chill thoroughly. Transfer the juice to a blender and, with the machine on, slowly add the olive oil and the remaining 1 tablespoon of grapeseed oil until emulsified. Pour the dressing into a bowl, add the remaining 1 teaspoon of lemon juice and season with salt and pepper.
In a very large bowl, toss the fennel with the endives. Add the crab and dressing and toss lightly. Season with salt and pepper and arrange the salad in a large serving bowl or on a platter. Drizzle the fennel oil all over the slaw, garnish with the parsley leaves and serve.
You can use lump crab meat, sweet claw meat from Maine crabs or king crab meat, which is the most expensive but also the most delicious.