Seared Cauliflower steak, Chimichurri & Pine nut Crumble

Name: Seared Cauliflower steak, Chimichurri & Pine nut Crumble
Cuisine: American, Latin American
Ingredients: ¼ cup avocado oil; 1 large head cauliflower, cut into four 1 inch-thick vertical slices. (optional: reserve florets that crumble); 1 Tbsp kosher salt; Freshly ground black pepper, to taste; 1 bunch parsley, stems removed; 1 bunch cilantro, stems and leaves; ¼ cup red wine vinegar; ¼ tsp red chili flakes; 2 garlic cloves; ¾ cup olive oil; 2 slices stale bread, roughly chopped; 1/4 cup pine nuts, toasted; 1/3 cup grated parmigiano reggiano cheese (substitute plant based cheese for vegan option); 1/4 cup chopped parsley leaves; 2 garlic cloves, smashed and diced; 3 tablespoons butter, melted, cooled (substitute plant based butter for vegan option)