Sprinkle the salmon with a pinch of salt (not listed in the ingredients) and let it sit for 10 minutes. Pat dry with a paper towel. Slice the zucchini into 1cm rounds. Trim the tops of the okra and cut them in half diagonally. Slice the lemon into rounds. Pluck the basil leaves.
Spread out 30cm of aluminum foil. Place the zucchini and okra on the foil and put the salmon on top. Add lemon slices and butter on the salmon, then sprinkle with black pepper. Close the foil packet and place it in a pan with 100ml of water. Cover with a lid and bring to a boil. Then, reduce to low heat and steam for 10 minutes. If the water runs low during steaming, add more.
Open the foil packet, tear the miso and basil leaves, and place them on top of the salmon.