After drying or cooking, nettles' formic acid content is neutralized and they are ready to eat. Nettles contain one of the highest amounts of protein of all greens, and also have many vitamins, minerals, trace elements in incredibly generous proportions. They have anti-inflammatory qualities as well.
Read all the way through this recipe before you begin.
Dice a medium onion and lots of garlic (3-4 large cloves) into enough olive oil to saute, and cook the onion-garlic mixture gently until it is translucent. Add 2 cups of hot water and 1 cup of dried lentils to the pot; simmer, loosely covered, for 25 minutes or until the lentils are cooked to the softness you like. Don't let them get over-cooked and mushy. If all the water is not absorbed at the end of cooking, drain the water out, so as not to make a soupy lasagna.
While the lentils are cooking, re-hydrate your dried nettles. (Or you can use fresh, see below.) For a 9x12 casserole pan of finished lasagna, use a cup or 1 1/2 cups dried nettles (can be purchased at Whole Foods Co-op) and pour over this, in a separate large bowl, about 2 cups of boiling water; stir, cover, and let the dried nettles re-hydrate for 20 minutes or so. Add more boiling water if they seem stiff and not re-hydrated enough, let sit a little longer, covered. If, after re-hydrating, the nettles are soupy, strain out the extra water. (Drink as tea!!) Press the water out with the back of a spoon in the strainer; otherwise the lasagna will be soupy.
If using fresh nettles, use the amount you would of spinach or other greens, which will cook down quickly to a much smaller amount than you would suspect!! You may want to use gloves when the nettles are fresh, or if you let them wilt on the cutting board for 20 minutes before chopping, that may take out their "bite." Use young nettles before they have flowered with their little grey-green, seedy/grainy - looking flowers. Chop the leaves and stems up so that you don't have long stems in your finished product, which people will struggle to cut through at table. (They made the bridge over the River Kwai with nettle stems.) Maybe 4-5 packed cups fresh nettles will cook down to a generous layer for the lasagna. You can just par-boil them for an instant if they are too "puffy" to make into a tidy layer in your casserole pan. Be sure to drain all excess water out.
Make your lasagna the way you usually do - usually in a 9x13 oven-proof, rectangular casserole pan, having cooked the amount of lasagna noodles you need for your layers. (Cook the lasagna noodles according to package directions.) I make 3 or 4 layers, so I use 12 whole lasagna noodles. Cook the noodles to al dente tenderness. Drain.
Now for the construction process! Pour a little olive oil and /or tomato sauce onto the bottom of your lasagna casserole dish, just to keep the noodles from sticking and burning onto the bottom of your pan. Add onto this the bottom layer of cooked lasagna noodles, then the layer of the cooked, seasoned lentils, then tomato sauce, noodle layer, nettle layer, tomato sauce, and so on. A layer of richotta cheese is nice, (drain this, too, if needed), then tomato sauce, noodles, and atop the whole thing a layer of tomato sauce and then generous slices of mozzarella cheese. Be somewhat sparing of the tomato sauce throughout; you want the finished product to be moist and spicey, but you don't want it to be so drowned in tomato sauce that you can't lift tidy squares out for servings.
Bake in a 350 degree oven for 30 - 45 minutes, until the sauce bubbles, and the mozzarella cheese on top is melted. Let sit for 5 minutes after removing from oven; this resting period makes it easier to slice through neatly. Serve generous squares and seconds!
A nice salad and garlic bread on the side are good accompaniments.