Japanese Salmon and Spinach Gratin

Place the spinach, salmon, and sliced leek in a bowl. Sprinkle over the flour and toss gently until everything is evenly coated.

Heat the butter and vegetable oil in a frying pan over medium heat. Once the butter has melted, add the salmon mixture and saute gently, separating the pieces so the salmon does not stick together.

When the salmon is lightly opaque on the outside and the flour no longer looks dry, pour in the milk and add the dashi stock granules. Stir carefully to combine without breaking up the salmon too much.

Add the crumbled tofu and cook for 3 to 5 minutes, stirring often, until the sauce thickens and coats the ingredients evenly.

Transfer the mixture to a baking dish. Top with the melting cheese, panko, grated hard cheese, and a small amount of butter if using. Bake in a preheated oven, toaster oven, or under a grill until the top is bubbling and golden brown.

Serve immediately while hot. If you like, you can substitute sliced parboiled potatoes for the spinach for a heartier variation.