Preheat the oven to 200 °C or 390 °F. Start to cook brown rice as per instructions on the package (optional). Whisk together all the ingredients for the ginger-garlic sauce until combined.
Fold 2 square pieces of parchment paper (at least 35 cm or 14 inches wide) in halves an then unfold. Divide the spinach evenly among the sheets of paper, placing it on one side of the crease. Put salmon fillets on top and drizzle with the ginger-garlic sauce. Season with salt and black pepper.
Fold the parchment paper as shown on the gif above, making an air-tight pocket. Bake for 12 minutes for medium. Unwrap and sprinkle with black sesame seeds. Serve with rice or other sides. Enjoy!