Method:
For the crab, stir together shallot, hot sauce, mayonnaise, mustard, lemon juice and chives in a medium bowl. Add crabmeat and lightly toss. Season with salt and pepper. Cover and chill.
For the rest of the salad, whisk together mustard, shallot, vinegar, chives and lemon juice. Slowly whisk in olive oil until dressing slightly thickens. Taste and adjust seasoning with salt and pepper. Set aside.
Steam Yukon gold potatoes until tender when pierced with a fork. While potatoes are still warm, pour a tablespoon or two of dressing over them.
Steam haricots verts until tender. Transfer to a boil of ice water to stop the cooking. Drain thoroughly. Combine haricots verts with watercress, endive and radish. Toss with a tablespoon of dressing.
Toss celeriac with remaining dressing in a small bowl.
To serve, arrange greens on a platter or individual plates. Top with crab, celeriac and eggs. Garnish with chives and serve immediately.