01 - Preheat oven to 350°F. Line a 9 x 5 inch loaf pan with parchment paper.
02 - Mix ground flaxseed with water in a small bowl. Let stand for 10 minutes until thickened.
03 - Heat olive oil in a large skillet over medium heat. Sauté onion, garlic, carrots, parsnips, celery, and mushrooms for 8-10 minutes until softened.
04 - Add sweet potato and cook for 5 minutes more, stirring occasionally. Remove from heat and let cool slightly.
05 - In a large bowl, combine sautéed vegetables, cooked lentils, oats, breadcrumbs, flax egg, tomato paste, soy sauce, smoked paprika, thyme, rosemary, salt, and pepper.
06 - Mix thoroughly using hands or a potato masher to slightly mash the mixture and help it hold together.
07 - Press mixture firmly into the prepared loaf pan. Smooth the top surface.
08 - Spread cranberry sauce or chutney over the top for a festive glaze, if desired.
09 - Bake for 45-55 minutes until firm and golden on top. Let rest in the pan for 10 minutes before slicing.
10 - Carefully lift out of the pan, slice, and serve with vegan gravy and sides of your choice.