Place coriander seeds and cumin seeds in a small dry skillet, then set over medium heat. Cook, shaking the pan often, until the spices are fragrant. Transfer to a mortar, then finely grind with a pestle. Set aside.
Heat olive oil over medium-high heat. Add pancetta and cook until crispy. Remove pancetta with a slotted spoon. Place in a paper-towel lined bowl to drain.
Preheat grill. When hot, place potatoes cut side down on grill. Cook, then remove.
Place grilled potatoes on a serving platter, then top with crisp pancetta and sliced snow peas. Drizzle everything with remaining olive oil, then sprinkle on dill, chives, truffle salt, and black pepper. Serve immediately or at room temperature.