My approach: An oniony mushroomy broth and lots of mushrooms and some root vegetables in a creamy a brown sauce topped with chopped chives and parsley and paprika, on your favorite egg noodles or pasta preference. By roasting the vegetables and boiling the onion skin for color, and adding a slight bit of soy sauce, gave the sauce plenty of depth to replace the meat. I added a little orange zest and Spanish paprika and clove because I tend toward Southern France or Spain when I cook beef stew type dishes so it is associated with beef in my mind, thus making me miss the beef less.
2 yellow onions, 3 cloves of garlic
Carrot, parsnip, potato, one large Portobello mushroom (or equivalent smaller)
Quartered Crimini or white mushrooms and sliced shitake mushrooms
White cheddar cheese
Milk, and one of these: Cream, sour cream, canned condensed non-fat milk, or whole milk yogurt/yogurt cheese (made by straining the yogurt overnight).
Olive oil and butter
Bay leaves, Thyme, Cloves, Chives, Parsley, Cayenne pepper, Spanish or Hungarian paprika
Salt, Pepper and Soy Sauce (or marmite)
Truffle oil or truffle salt (optional)
Oniony vegetable base
Cut prepared carrots and parsnips in into coin shaped slices that are then quartered or cubed to make bite sized pieces. Slice onion into ½ wedges. Drizzle a little oil on bowl of vegetables, add Salt and Pepper and mix together. Coat the bottom of a roasting pan with olive, sunflower, or other oil. Toss the vegetables, bay leaves, and thyme, the onion skins, into the roasting pan and roast in the oven for 1 hour at a low temp like 325degrees. Stir about every 15 minutes. Add a little water if they begin to dry out too much. Put one potato in the oven by itself while roasting the vegetables. Take the potato out when it is nice and squishy after about 1 hour.
Turn the oven up to 375 and add two large Portobello mushrooms sliced and diced, stirring well. Add a little water if necessary to coat the vegetables better when you stir. Roast at this temperature 15 minutes or until portobello is cooked. The veggies should be just sticking to the bottom of the pan, but not burned or too dried out.
Pasta: in the meantime, you can cook your pasta to a chewy consistency so it doesn’t turn to mush later. Your favorite stroganoff noodle will do just fine. I also like a corkscrew noodle or some imported (woops, not local) fancy chewier egg noodles that have extra eggy flavor. Drain the pasta and place it in an oven proof casserole with salt, pepper and enough butter to keep the noodles form getting sticky.
Mushrooms: Also in the meantime, slice and sauté in butter a couple dozen crimini mushrooms and maybe 8 thinly sliced Shitake mushrooms, with tough part of the stem removed. (You can also add these to the vegetable roast a little bit after the Portobello pieces. But I wanted to protect these from roasting so I cooked them separately). Place them in the casserole dish.
Roux: Combine flour and butter and milk to make a roux. Maybe 3 Tablespoons of butter to ¼ cup of flour and add milk to thin. (Sorry, I didn’t measure precisely).
Broth: When the roasted vegetables are done, take out the vegetables and put them in the casserole dish. (You may wish to discard the carrot and parsnip at this point if you don't want to bite in to a non-traditonal flavor in the stroganoff). Toss the onion skin back in the roasting pan. Add 1or more cups of water and 1 teaspoon of soy sauce or marmite (yeast extract), a clove or two and boil, stirring to release the stuck on flavors of the roasted vegetables. Strain the liquid.
Casserole: So you have your casserole dish with the pasta, the veggies, the mushrooms and now you need to finish your sauce.
Sauce finale: Combine roasted vegetable broth, 1 peeled mashed potato and flour roux, adding broth or milk as necessary to create a sauce. Add salt and pepper to taste and one dash or cayenne pepper. Add the orange zest about 1 teaspoon full. Add 1 T of tomato paste or 1/3 cup Red or Marsala wine. (I used tomato sauce form a tube) Simmer for 5 minutes. Stir in sour cream . You could add yogurt or cream at this point instead of sour cream and try reduced condensed milk or cream instead of the flour roux, but the roux will help the sauce not get sopped up by the pasta so easily.
Topping: little bit of finely grated white cheddar cheese or else toasted buttered bread crumbs
Drizzle of truffle oil or sprinkle of truffle salt on top
Dash of Spanish smoked paprika or Hungarian paprika across the top
Fresh chopped parsley
Fresh chopped chives
You can place this in the fridge for a later reheating, but the pasta will absorb liquid so make sure you have enough sauce if you do this and be prepared to revive the sauce with some broth and a little cream or evaporated milk.
Place in a hot oven about 375 degrees, 20 minutes or more before serving to heat.
For upped protein content, add garbanzo beans to the veggie roast, add firm tofu or tempeh slices that have been browned with a little soy sauce and oil , or add cubes of aged gouda cheese to the casserole dish., Also good would be egg plant chunks. To make the flavor less earthy, take out the rutabaga. My daughter is not fond of the flavor, but I find it adds a satisfying complexity.
To simplify this recipe: Omit things or substitute with what you have on hand, use only one kind of mushroom and use purchased vegetable broth and onion soup to mix with the roux. Sautee onions and mushrooms.
Vegans could try this by choosing a pasta without eggs and omitting the dairy and using cashew cream, cashew butter whipped with water until sauce consistency.
Now I need my recipe tester/tweakers (you) to get the proportions right. Let me know!