1. Prepare the Cabbage Leaves:

• Core the Cabbage: Using a sharp paring knife, carefully cut around the core at the base of the cabbage in a cone shape and remove it. This helps the leaves separate more easily.
• Boil Water: Bring a large stockpot of water to a rolling boil. Add about 1 tablespoon of salt (this helps season the leaves slightly).
• Blanch the Cabbage: Gently place the whole cored cabbage into the boiling water, core-side down initially. As the outer leaves soften (after about 2-3 minutes), use tongs to carefully peel them off one by one. Place the softened leaves in a colander to drain and cool. Continue this process until you have about 12-15 large, pliable leaves. You may need to dunk the cabbage back in for a minute or two between peeling layers. Don’t overcook the leaves – they should be flexible but not mushy. You’ll likely have smaller inner leaves left; you can chop these up and add them to the sauce or filling later, or save them for another use (like soups or stir-fries).
• Prepare Leaves for Rolling: Once the leaves are cool enough to handle, lay one flat. If the thick rib at the base of the leaf is very prominent and stiff, carefully shave it down with your paring knife, making it thinner and more flexible, but be careful not to cut through the leaf. Set the prepared leaves aside.

2. Make the Savory Filling:

• Sauté Aromatics: Heat 1 tablespoon of olive oil in a large skillet or pot over medium heat. Add the finely chopped onion, carrots, and celery (the mirepoix). Sauté for 5-7 minutes, stirring occasionally, until softened and the onion is translucent.
• Add Mushrooms & Garlic: If using mushrooms, add them now. Cook, stirring occasionally, until they release their liquid and start to brown (about 5-7 minutes). This browning develops crucial umami flavour. Stir in the minced garlic and cook for another minute until fragrant.
• Combine Filling Ingredients: Stir in the rinsed brown rice, rinsed lentils, smoked paprika, dried thyme, and ground cumin. Stir well to coat everything with the spices and toast them slightly (about 1 minute).
• Cook the Filling: Pour in the 2.5 cups of vegetable broth or water. Bring the mixture to a simmer. Once simmering, reduce the heat to low, cover the pot tightly, and cook for 35-45 minutes, or until the lentils and rice are tender and most of the liquid has been absorbed. Check occasionally towards the end and add a splash more broth/water if it looks too dry before the rice/lentils are cooked.
• Finish the Filling: Remove the pot from the heat. Let it sit, covered, for 5-10 minutes to steam. Fluff the mixture with a fork. Stir in the chopped fresh parsley and nutritional yeast (if using). Taste and season generously with salt and freshly ground black pepper. This is your last chance to adjust the filling’s seasoning before rolling! If the mixture seems very wet or loose, stir in the optional breadcrumbs or oats to help bind it. Let the filling cool slightly while you prepare the sauce base – it’s easier to handle when not piping hot.

3. Prepare the Tomato Sauce Base:

• Sauté Onion & Garlic: In the large pot or Dutch oven you plan to cook the cabbage rolls in (it should be large enough to hold them snugly in a single or double layer), heat 1 tablespoon of olive oil over medium heat. Add the remaining finely chopped large onion and sauté until softened, about 5 minutes. Stir in the minced garlic and cook for 1 minute more until fragrant.
• Build the Sauce: Stir in the tomato paste and cook for 1 minute, stirring constantly, to deepen its flavour. Pour in the crushed tomatoes, diced tomatoes (with their juice), vegetable broth, oregano, paprika, and the bay leaf. Add the optional maple syrup/sugar if using. Season with a pinch of salt and pepper (you’ll adjust more later).
• Simmer Briefly: Bring the sauce to a gentle simmer, then reduce the heat to low. Let it bubble gently while you assemble the rolls. Optional: If you have leftover chopped cabbage from preparing the leaves, you can add some to the sauce now for extra texture and flavour.

4. Assemble the Cabbage Rolls:

• Prepare Your Station: Have your softened cabbage leaves, the slightly cooled filling, and the pot with the simmering sauce base ready.
• Fill and Roll: Lay one cabbage leaf flat on your work surface, with the base (where the stem was) closest to you. Place about 1/3 to 1/2 cup of the filling (depending on the size of the leaf) near the base of the leaf in a log shape. Fold the stem end up over the filling. Fold the two sides of the leaf inwards, over the filling (like making a burrito). Then, starting from the end closest to you, roll the cabbage leaf up tightly towards the tip.
• Repeat: Continue this process with the remaining leaves and filling until you’ve used it all up. You should have 10-12 rolls. Don’t worry if they aren’t all perfectly uniform!

5. Simmer to Perfection:

• Arrange Rolls in Pot: Carefully place the assembled cabbage rolls, seam-side down, into the pot with the simmering tomato sauce. Nestle them snugly together. They can be in a single layer or two layers if necessary. If layering, spoon a little sauce between the layers. Ensure the sauce comes at least halfway up the sides of the rolls; add a splash more broth or water if needed to achieve this, but don’t completely submerge them.
• Simmer Gently: Bring the sauce back to a gentle simmer over medium-low heat. Once simmering, reduce the heat to low, cover the pot tightly, and let the cabbage rolls cook gently for 45 minutes to 1 hour. The cabbage should be very tender, and the flavours beautifully melded. Avoid boiling, as this can cause the rolls to fall apart. Check occasionally to make sure the sauce isn’t sticking or reducing too much; add a splash of broth if needed.
• Rest: Once cooked, turn off the heat and let the cabbage rolls rest in the pot, covered, for at least 10-15 minutes before serving. This allows the flavours to settle and makes them easier to handle. Carefully remove the bay leaf before serving.