At least 1 hour before grilling, soak wood chips in enough water to cover. Drain before using.
In a small saucepan, combine honey and chile pepper or chili powder. Cook and stir over medium-low heat until heated through. Remove from heat; stir in oil. Brush some of the mixture over the beef tenderloin. Season beef with black pepper and salt.
For a charcoal grill, arrange preheated coals around a drip pan. Test for medium heat above the drip pan. Sprinkle wood chips over coals. Pour 1 inch of water into the drip pan. Place roast on grill rack directly over the drip pan. Cover and grill for 40 to 50 minutes or until an instant-read thermometer inserted near the center of the roast registers 135°F, brushing with honey mixture occasionally during the first 20 minutes of grilling. Discard any remaining honey mixture.
Remove meat from grill; cover with foil. Let stand for 10 to 15 minutes before slicing. The temperature after standing should be 145°F for medium-rare. Transfer to a serving platter. If desired, garnish with watercress, key limes, kumquats and tangerine wedges.
Tip: To grind ancho chile peppers, place dried, seeded and stemmed ancho chile peppers in a blender. Cover and blend until ground.