Preheat oven to 400°F (200°C).
To a small pot, add 1 cup dried black lentils, 1 bay leaf, 1 piece kombu*, and 3 cups vegetable stock. Bring to a boil and reduce heat to simmer. Cook for 15-20 minutes or until soft, stirring occasionally. Remove from heat and once cooled, remove any excess liquid and set aside.
While the lentils are cooking, in a small bowl, add 2 tbsp olive oil, 1 tsp garlic powder, 1 tsp onion powder, ½ tsp each paprika, salt, and pepper and ¼ tsp chili powder. Whisk together. Brush this mixture evenly over your cauliflower steaks, flip and brush the other side. Place steaks on a parchment lined baking tray.
When lentils are done and excess liquid removed, add them to the tray. Bake for 15 minutes, then flip the cauliflower pieces and cook for another 10-15 minutes or until fork tender.
While cauliflower is roasting, to a blender add 1 large roasted red bell pepper, ½ cup hazelnuts, ¼ cup cashews, ¼ cup tomato sauce, ¼ cup parsley, ¼ cup breadcrumbs, 3-4 cloves garlic, 2 tbsp sherry cooking wine, 1 tsp smoked paprika, ½ tsp each cayenne pepper and sea salt, and ¼ tsp garlic powder and onion powder. Start blender and while blending, drizzle in ¼ cup olive oil or more to taste/desired smoothness.
To assemble, pour ¼ of the romesco sauce onto a plate or bowl. Top with one of the cauliflower steaks and ¼ of the black lentils.