In a large skillet over medium high heat, brown the meat. Break up large pieces and cook until done but not overly crumbly. Add the onion, bell pepper, and garlic, stir, and continue to cook until the vegetables are tender.
Add all of the spices, herbs, and tomato paste. Stir and cook for several minutes.
Add the red wine, stir, and cook until all of the liquid has absorbed or evaporated, about 5 minutes.
Add the tomato puree, stir, and simmer over low heat for about 20 minutes.
To make the Bechamel sauce:
Melt the butter in a medium sized saucepan over medium high heat. Whisk in the flour, whisk constantly, and allow to cook until the flour is golden brown and smells heavenly. While continuously whisking, add in the milk and bay leaf. Continue to cook while stirring until thickened. Stir in salt, pepper, and nutmeg. Discard bay leaf. Remove from heat.
Allow mixture to cool and when it is cool enough to touch, whisk in the egg yolks and the lemon zest until smooth.
To prepare the eggplant:
Remove half of the peel by peeling vertical strips. I like to remove half because I find that not removing any peel makes it too hard to eat, but I like some peel because it helps the pieces stay in tact. Slice into 1/4 inch thick rounds.
Combine water and salt in large bowl and stir until salt dissolves. Add eggplant slices to brine, weigh down with heavy lid to keep them submerged, and soak for at least 15 minutes.
Remove eggplant from brine. Set slices in single layer in between clean towels or paper towels and press to remove liquid.
You may have to do this next part in batches. Set eggplant slices in a single layer on a baking sheet and lightly coat with olive oil. Broil for a few minutes on each side, just to the point where they're softened and the edges begin to brown. Remove from oven and set aside.
To prepare the potatoes:
Peel and slice the potatoes into 1/4 inch rounds. Add salt to a large pot of water, bring to a boil, and add potatoes. Cook them until they're slightly soft/slightly crunchy, about 5 minutes. They will continue cooking later in the oven. Drain and set aside.
To assemble Moussaka:
Preheat oven to 350 degrees F.
Spread all of the potatoes across the bottom of an 11x17 baking dish. Spread half of the eggplant on top of the potatoes. Add all of the meat sauce on top of the eggplant, then top with the remaining eggplant. Cover everything with the Bechemel sauce and then top with the grated cheese.
Bake in preheated oven until browned and bubbly, about 35-40 minutes. Best if you let it cool for about 20 minutes before serving. Enjoy!