This excellent vegan dish is a variation on Grilled Zucchini Lasagna with Roasted Red Pepper Sauce from Stephen Raichlen's book, High-Flavor Low-Fat Vegetarian Cooking (1995). I feel sliced roasted red peppers complement zucchini slices better than does the roasted red pepper sauce which Raichlen's recipe uses.
This dish typically takes me more than 3 hours to cook, although the work can be split across different days (I do not claim to be a fast cook). This lasagna isn't as filling as that which uses cheese, and subsequently tends to get eaten up quickly.4 medium red bell peppers
Roast the red peppers. On a gas stove, I find this works well by using a single large burner, removing the burner's grill (which normally supports a pot), and using metal tongs to position the peppers as necessary to burn as much of the skin as possible. It will likely be necessary to hold each of the peppers directly over flame one at a time to burn some areas of the skin (e.g., the areas which are indented which can't get burned even though that side of the pepper is in the flame). When the peppers are completely blackened, wrap them in wet paper towels and put them in a paper bag for several minutes, which helps loosen the skins (it's like a little sauna for the peppers) and allows them to cool. This process will likely make the area smell of roasted red peppers, so ample ventilation will be helpful.
Peel off the skins of the peppers. The burned sections should come off easily using your fingers. A sharp knife helps remove sections which weren't completely burned. Remove the seeds and the stems (and any new peppers starting to sprout inside). Cut or tear them the long way into pieces that are 1 to 2 inches thick.
Over medium-low heat, heat enough olive oil (probably a couple of tablespoons) to fry the garlic and onions until they are soft. In a bowl, mix this with the broth and the bread crumbs to make the filling mixture, which should have some substance but doesn't need to be particularly thick. Set aside. Excess juice from the peppers or the zucchini can be mixed in.
Wash and cut the zucchinis in half the short way (across their diameters). Cut each half into 1/4 inch thick slices the long way. The more uniform the thickness, the easier it will be to cook the zucchinis uniformly.
Over medium-low heat, cook the zucchini sections in olive oil till they are soft but not limp. Watch them closely so you can flip them before they brown. You should be able to see the bottom edges turning a pleasant and appetizing green, which should be around the time they should be flipped. Ideally you'd only need to flip each piece over once.
Boil enough water such that the lasagna noodles can be totally submerged in the pot when turned on their side the long way (not when they're flat on the bottom of the pot). If the pot is not large enough to let them be completely submerged immediately, submerge them when their underwater sections are soft enough to bend without breaking, so that the whole of each noodle can be cooked. Cook for 9-10 minutes or until the lasagna noodles are soft enough based on a taste test.
Apply a light layer of spray oil to the bottom of a 9" x 13" baking pan. Lay down 3 lasagna noodles, covering the bottom of the pan. Lay down alternating pieces of peppers and zucchini, as if you were making a checkerboard with 9 rectangular squares, alternating red and green. That is, each lasagna noodle will have one type of vegetable on one of its thirds, and the other type of vegetable on its other two thirds (imagine each noodle being divided into thirds the short way). Pour on half of the filling mixture and spread it evenly. Lay down 3 more noodles. Put down another layer of peppers and zucchini, but this time put peppers over where zucchini is in the lower layer, and vice versa. Pour on the remaining half of the filling mixture and spread it evenly. Put down the top layer of noodles.
Cover the lasagna with foil and bake at 350 degrees for 30-40 minutes. If you like the top a little bit crispy, remove the foil and bake uncovered for an additional 5 minutes or so, but watch it carefully so it doesn't get too crispy, especially at the edges.
Raichlen's original recipe said you could prepare the lasagna up to 24 hours ahead up, and postpone baking it until the following day. I cooked all the vegetable components (plus the garlic) one day and did all the rest the following day and had a good result.
Ken Ho's recipe corner
Ken Ho's home page