Peel and slice the sweet potatoes and simmer in lightly salted water for 15 minutes or until soft.
Meanwhile mix the bread crumbs, lime zest and juice and chopped parsley together. Season fish, spread tartar sauce over fish and add bread crumb mixture on top.
Pan fry for 3 minutes on a medium heat and then transfer to a grill for another 3-5 minutes or until crisp and golden on top.
When the sweet potatoes are softened removed from water and mash, adding butter and seasoning to taste. Using two large spoons quenelle the sweet potato mash onto a plate. Place the crispy Pollack fillets on top and add a little lime juice to finish.