Use a spoon to remove brown stuff from the Portobello mushroom cap and cut into thin slices. Mix sliced mushroom and cherry tomatoes with 1 tbsp oil, pepper, garlic and salt by tossing to coat well. Spread on a dehydrator sheet and dehydrate at 135°F (57°C) for 1 to 2 hours. The mushrooms should look slightly cooked or soft.
In the meantime, peel parsnip and carrots into thin ribbons with a vegetable peeler. Pour into a large-size bowl and drizzle a little olive oil over vegetables.
Mix carrot and parsnip fettuccine with the pumpkin seed pesto by tossing. Use your hands to work pesto into "fettuccine" because the pesto can be quite thick. The coated vegetable should be well mixed with the marinated mushrooms and cherry tomatoes. Trickle with pumpkin seeds and serve.