Preheat oven to 400°F. and move one rack to the top slot in the oven.
For the sauce, cut the tomatoes in half and grate on a box grater, discarding the remaining skins. Cook on medium-low heat in a wide, nonreactive skillet with garlic until thickened into a sauce, about 15 minutes. Season with salt to taste.
Prep all your veggies while the tomato sauce is cooking. In a small bowl, mix all the herb-seasoning ingredients and set aside. Spread tomato sauce on the bottom of a 9x9-inch baking dish. Stack veggies by alternating layers of potatoes, tomatoes, peppers, eggplant, and tomatillos. Spoon the herb seasoning over the vegetables.
Cover with foil and bake for 20 minutes, remove foil, and bake for an additional 10 minutes. Move pan to top rack and broil for 2 additional minutes to add some char to the veggies.