Put the vinegar, soy sauce, ginger, garlic, peanut butter, chili oil, honey and sesame oil in a blender and blend until smooth. With the motor running, slowly add the canola oil until emulsified. If the vinaigrette is too thick, thin with a little warm water. Season, to taste, with salt and pepper.
For the salad:
Heat grill to high. Brush the radicchio with oil and season with salt and pepper, to taste. Grill until lightly golden brown. Arrange radicchio, endive and watercress on a platter and drizzle with the peanut vinaigrette. Garnish with peanuts, chives and cilantro.