Add the blended oil, garlic and kombu to a large saute pan and turn the heat on medium. Once the garlic is fragrant, add the portobello mushrooms. Allow the portobellos to confit, flipping every 5 minutes, until softened throughout, 15 to 20 minutes.
Remove the portobellos from the oil and let cool.
In a high-powered blender, combine the panko with the nori powder and mushroom powder. Quickly blend until mixed.
Preheat the neutral oil in a deep fryer to 350 degrees F. Line a sheet tray with a wire rack.
Set up a standard breading station with the flour, eggs and the panko/nori/mushroom powder mixture each in shallow dishes. Bread the mushrooms first in the flour, then the eggs and finally the panko mixture and fry until browned and crispy, about 5 minutes. Remove from the oil and drain on the wire rack. Season with salt and pepper.
Slice, garnish with small dill sprigs and serve with the Mushroom Tartar on the side.
Mushroom Tartar Sauce:
Add the white button mushrooms, cream and salt to a medium saucepan and cook over medium heat until the mushrooms are softened, about 10 minutes. Strain the mushrooms over a small saucepan, then add them to a blender and blend into a paste. Carefully stream in the heated cream, blending, until the texture is similar to mayonnaise. Transfer to a bowl and fold in the pickles, capers, dill and parsley and season with salt and pepper. Chill in the refrigerator until ready to serve.