Preheat oven to 350 degrees F.
In a medium saucepan, heat olive oil over medium-high heat. Add leeks and garlic and saute until translucent, about 1 1/2 minutes. Add zucchini and the fennel and saute for another minute. Add artichoke hearts and crushed tomatoes. Bring to a simmer and then add oregano. Stir and remove from heat.
Cover the bottom of a 13 by 9-inch pan with 1 cup of the tomato mixture. Top with 2 lasagna noodles. Top with half of the remaining tomato mixture. Sprinkle with feta cheese. Add remaining 2 lasagna noodles and top with remaining tomato mixture.
Sprinkle with mozzarella. Bake for 35 minutes or until bubbly. Let stand for 5 minutes before serving.
