Step 1Char the bell pepper over a burner or under a broiler until it is well-blackened on all sides. Wrap in a plastic bag and set aside until cool enough to handle, then peel and seed the pepper. Set aside.
Step 2Heat the oil in a large skillet over high heat. Add the chiles de árbol and habanero and toast until fragrant, about 3 minutes; toward the end of toasting, add the pine nuts and almonds and toast until fragrant.
Step 3Add the tomatillos, tomatoes, water and three-fourths teaspoon salt, and cook over high heat until the tomatillos are tender, about 5 minutes.
Step 4Purée in a blender until smooth, add the red wine vinegar and adjust seasoning. The salsa should be thick enough to generously coat the back of a spoon. This makes about 1 quart of salsa, more than enough for the recipe. The remainder will keep, covered tightly, in the refrigerator for a week.
Step 1Wrap the sweet potatoes tightly in microwave-proof plastic wrap and microwave on high until tender, 13 to 14 minutes.
Step 2Bring the white wine, thyme and parsley to a boil in a large saucepan and cook until it loses the raw alcohol smell, about 5 minutes. Reduce the heat to a bare simmer.
Step 3Trim and discard the tough green parts from the leeks, then cut them in ½-inch lengthwise strips, leaving them attached at the root. Swirl in water to remove any sand. Pat dry and salt lightly.
Step 4Heat 2 tablespoons olive oil in a large skillet over medium-high heat and add the leeks. Cook until well-browned, 5 minutes, then turn, add 1 tablespoon butter, and sear on the other side, another 3 to 4 minutes. Add to the white wine in the saucepan.
Step 5Add 2 tablespoons butter to the same skillet and when it is foaming add the carrots and cook until browned on one side, about 5 minutes. Turn the carrots over, add the whole unpeeled garlic cloves and cook until the carrots are browned on the second side, about 4 more minutes. Add the carrots to the wine wine and leeks.
Step 6Deglaze the skillet with some of the white wine, scraping up any residue that’s stuck to the bottom of the pan, add it back to the saucepan and cook gently until the leeks are tender, about 30 minutes. The leeks can stay in the liquid off heat for several hours.
Step 7When almost ready to serve, heat 2 tablespoons butter in a skillet over medium-high heat. Pull the leeks from the cooking liquid, pat them dry and add to the butter to cook briefly on both sides, about 3 minutes total. Remove, cut away the bases and cut the tops into 2-inch lengths.
Step 8Slice the unpeeled roasted sweet potatoes a little more than ½ inch thick. If the flesh has shrunk from the peel, remove it. Heat 2 tablespoons butter in a nonstick skillet over medium-high heat. Brown the sweet potatoes on both sides, about 5 minutes total, turning them carefully to keep them intact. Once they have browned, break up each slice into rough pieces to make them easier to eat.
Step 9For each taco, heat 2 tortillas on a griddle or in a large skillet over medium-high heat with a little butter. Place 2 slices of Oaxaca cheese next to them on the griddle and when the tortillas are warmed through, stack them on top of the cheese. You can do this with as many tortillas as will fit on the griddle.
Step 10When the cheese has browned on one side, remove the tortillas and cheese to a plate, cheese-side up.
Step 11Add 2 to 3 strips of leek and some sweet potato. Spoon over 1½ to 2 teaspoons salsa and sprinkle with 2 teaspoons crumbled feta, a few toasted pine nuts and 1 teaspoon minced green onions and serve immediately. Repeat using the remaining ingredients.