Prep time: 5 minutes
Cooking time: 5 minutes
Place the fish in a pan and add the milk and the bay leaf. Bring to a simmer and gently poach for 2 mins until opaque and just cooked. Lift out the fish, remove the skin and flake. Reserve the milk for the base of the rarebit sauce (discard the bay leaf).
Heat grill to high. Melt the butter in a small pan, then stir in the cornflour and cook for 1 minute or until you have a sand like consistency. Gradually whisk the reserved poaching milk in. Cook, whisking all the time, until the sauce is thickened and smooth. Stir in the mustard and most of the cheese and season with black pepper.
Top the toast with the flaked cooked fish, spoon over the sauce and scatter with the remaining cheese. Grill until golden and bubbling. Serve hot with a crispy side salad and fresh tomatoes.
The sauce needs to be fairly thick to sit on top of the fish, but the consistency can be adjusted to suit individual taste. Use any smoked fish that you have available.