Preheat oven to 375 degrees F. Toss the sliced potatoes into a bowl with 2 Tablespoons of oil and some salt and pepper to taste. Taking one slice of potato at a time, start lining the edges of a pie pan, making sure the potatoes are slightly over lapping each other. Once the edges are lined, start laying the potatoes on the bottom of the pie dish, starting on the outside edge and working your way in, again making sure to overlap the potatoes slightly. Once done, place the potatoes in the oven for 20 minutes. While the potato crust is in the oven, heat the remaining 1 Tablespoon of oil in a skillet. Add the zucchini, onion, asparagus. Sauté veggies for 4-5 minutes or until they just start to become tender. Stir in the garlic and cook 1-2 more minutes. Remove from heat and stir in spinach, salt, pepper and oregano.