Preheat your oven to 180°C (350°F) and lightly oil a 9x5 inch loaf pan, or line it with parchment paper.
In a small bowl, whisk together the ground flaxseed and water to create a flax egg. Let it sit for about 5 minutes until thickened and gelatinous.
1 cup cooked lentils
In a large mixing bowl, combine the cooked lentils and finely chopped mushrooms. Use a fork or potato masher to mash everything together until the mixture is well blended but still slightly chunky.
1 cup cooked lentils
Add the breadcrumbs to the lentil mixture and stir to incorporate, creating a cohesive base.
1 cup cooked lentils
Pour in the soy sauce and tomato paste, then sprinkle the smoked paprika and onion powder over the mixture. Mix thoroughly to evenly distribute the spices and liquids.
1 cup cooked lentils
Stir in the prepared flax egg until the mixture becomes sticky and holds together when pressed. Adjust with a little water if it’s too dry.
1 cup cooked lentils
Transfer the mixture into your prepared loaf pan, pressing down firmly with the back of a spoon or spatula to shape it evenly and compactly.
Bake the loaf in the oven for about 45-50 minutes, until the top is golden brown and the loaf feels firm when gently pressed.
Remove the loaf from the oven and let it rest in the pan for about 10 minutes. This helps it set and makes slicing easier.
Carefully lift the loaf out of the pan and transfer it onto a wire rack. Allow it to cool for a few minutes before slicing to prevent crumbling.
Slice the vegan meatloaf into thick portions, and serve warm or at room temperature with your favorite sides or a drizzle of sauce for extra flavor.