Combine coriander seeds, cumin seeds, fennel seeds, 1/4 teaspoon salt, and black pepper in a spice grinder, and process until finely ground. Brush canola oil over pork tenderloin. Rub with spice mixture. Place pork on a roasting rack in pan; let stand at room temperature 30 minutes. Preheat oven to 425°. Roast pork at 425° for 15 minutes or until a thermometer registers 145°. Let stand for 5 minutes; slice. Squeeze moisture from cucumber. Combine cucumber, yogurt, lemon rind, 1/4 teaspoon salt, ground red pepper, and minced garlic. Serve with pork.