To make Dressing: Whisk together mayonnaise, truffle oil, chives, mustard, and vinegar in bowl. Whisk in olive oil. Season with salt and pepper, if desired.
To make Salad: Preheat oven to 400°F. Toss potatoes with canola oil on baking sheet, then spread into single layer, and season with salt and pepper, if desired. Bake 25 minutes, or until golden brown, turning occasionally.
Toss frisée with Dressing. Arrange potatoes on platter, top with frisée, and garnish with tomatoes, radishes, and pistachios.