Preheat the oven to 350 degrees F and line a loaf pan with parchment paper.
Heat olive oil in a large sauté pan set over high heat and add in diced onions. Sauté on high, stirring 3 minutes, then reduce temperature to low and let caramelize. When onions are lightly golden brown, add in diced celery and carrots. Cook to soften (5 to 8 minutes). Turn off the heat and set it aside.
In a small bowl combine the flax meal with water. Set aside.
Place walnuts, sun-dried tomatoes, coconut aminos (or tamari/soy sauce), vinegar, cumin, chili powder, paprika, cayenne, onion powder, garlic powder, and salt in the bowl of a food processor and process until roughly combined and resembles the texture of ground meat, adding in a little water if necessary.
Transfer the walnut mixture to a large bowl and stir in the onion and flax mixture from steps 2 and 3. Stir to combine.
Lightly press walnut mixture into prepared loaf pan and place in oven. Bake the loaf for 40 minutes, or until the top has browned. Allow it to sit for 15 minutes before slicing and serving.
Serve with a scoop of mashed potatoes and steamed veggies, or sides of choice!
If you'd like to glaze the loaf, spread a thin layer of tomato sauce or organic ketchup over the top of the loaf before serving.
Walnuts are rich in heart-healthy fats, such as omega-3, magnesium, and antioxidants!