Wild garlic miso
1. Place the cod fillet in a dish or baking tray and sprinkle over the rock salt to cover. Leave to salt for 7 minutes.
2. Meanwhile, place the miso, wild garlic leaves and water in a blender and blitz together until smooth. Gradually add the oil while continuing to blend and allow the mixture to emulsify (as if making a mayonnaise). When fully combined, season to taste with a little lemon juice and salt.
3. After 7 minutes rinse the salt from the cod under cold water and pat the fish dry with kitchen paper. Cut into 4 equal portions and set aside.
4. If using a barbecue, preheat to high. Alternatively, a hot griddle pan can be used.
5. To cook the cod, place the butter in a pan and cook over a high heat to create a brown butter (beurre noisette). As soon as the butter starts to foam and is lightly golden with a nutty aroma, remove from the heat and cool quickly to stop it from burning.
6. Pour the butter into a wide pan (large enough to fit all 4 pieces of cod) and warm through gently to 60°C. Add the cod and gently poach for 5 minutes on each side, being careful to keep the temperature low.
7. While poaching, barbecue or griddle the asparagus spears for 2 minutes until tender, turning regularly. Thinly slice the cooked spears into 2mm thick rounds and season with a little lemon juice, salt and some of the butter from cooking the cod.
8. To serve, spoon a generous amount of the wild garlic miso into each serving dish. Drain the cod from the butter and pull apart into large flakes. Dress these with a little more salt, lemon juice and butter and add to the dishes.
9. Scatter over the asparagus slices and garnish with the reserved wild garlic flowers and a grating of bottarga.