Blanch the spinach: Bring a pot of water to the boil and add a little salt (optional). Blanch the spinach for about 1 minute, until just slightly softened, then remove.
Adding salt to the water helps keep the spinach a vibrant green. Transfer the spinach to iced or cold water straight after blanching. This stops the residual heat from turning it yellow.
Squeeze out the water: Once the spinach has cooled, gently squeeze out the excess water by hand. Don't squeeze too hard, or the spinach will become too soft and lose its texture.
Season: Cut the spinach into bite-sized lengths if needed. Add the garlic, soy sauce, sesame oil, seasoning powder or MSG (optional), and sesame seeds. Toss well and adjust to taste.
The seasoning powder adds a touch of extra umami, but it's completely optional. Soy sauce alone works just fine.