Toast the sunflower seeds on a pan over medium heat. Remove them.
Now preheat the same pan to high heat and add the butter. Immediately add the spinach (throughly washed and dried) and salt . The salt should go into the pan with the spinach as it helps to keep it bright green.
Stir the spinach on the pan until wilted and remove. Mix about half the seeds into the spinach.
Place the spinach at the center of the dish and then the fish on top of them. Finish with the sauce, sunflower seeds and a few chili flakes if desired.