Vegetarian Moussaka

Step 1
Sprinkle eggplant slices with salt; set aside for 30 minutes. Rinse and pat dry with paper towels.

Step 2
Preheat the oven to 375 degrees F (190 degrees C).

Step 3
Heat olive oil in a large skillet over medium-high heat. Cook eggplant and zucchini in hot oil until lightly browned, about 3 minutes per side. Remove with a slotted spoon to drain on a paper towel-lined plate, reserving as much oil as possible in the skillet.

Step 4
Add more oil to the skillet if needed and let it get hot. Cook potato slices in hot oil until browned, 3 to 5 minutes per side. Remove with a slotted spoon to drain on a paper towel-lined plate, again reserving oil in the skillet.

Step 5
Saut? onion and garlic in reserved oil until lightly browned, 5 to 7 minutes. Pour in vinegar, bring to a boil, and reduce heat to medium-low; cook until liquid is reduced in volume and thick. Stir in tomatoes, lentils, 1/2 of the juice from lentils, parsley, and oregano. Season with salt and black pepper. Cover, reduce heat to medium-low, and simmer for 15 minutes.

Step 6
Layer about 1/3 of the eggplant, 1/3 of the zucchini, 1/2 of the potatoes, and 1/2 of the feta in a 9×13-inch baking dish. Pour 1/2 of the tomato mixture over vegetables; repeat layering, finishing with a layer of eggplant and zucchini.

Step 7
Cover and bake in the preheated oven for 25 minutes.

Step 8
Meanwhile, make the sauce: Stir milk, flour, and butter for together in a small saucepan; bring to a low boil, whisking constantly, until thick and smooth. Season with nutmeg and black pepper. Remove from heat, cool for 5 minutes, and stir in beaten egg.

Step 9
Pour sauce over vegetables and top with Parmesan cheese. Continue baking, uncovered, until sauce is bubbly and top is lightly brown, 25 to 30 minutes.