Make the marinade: 
Mix all marinade ingredients in a bowl.

Prep the tempeh: 
Pierce the block of tempeh all over with a skewer. Inject or drizzle marinade into the holes so the flavors soak deep. Place in a container, pour the rest of the marinade on top, seal, and marinate for a few hours (or overnight).

Roast the veggies:
Toss potatoes, sweet potato, carrot, and onion with olive oil, salt, and pepper. Roast at 200°C for about 30-35 minutes until golden and crisp.

Bake the tempeh:
Transfer marinated tempeh to a baking sheet. Sprinkle the tempeh generously with coarse spice mix so the tempeh is completely covered. Bake at 180°C for about 45 minutes until the outside is caramelized and fragrant.

Serve:
Slice the tempeh and serve warm or cold with the roasted veggies on the side and ketchup for dipping.