Bring a large pot of water to a boil. Toss in the spinach and blanch it for about 30 seconds to 1 minute, just until wilted.
Quickly drain the spinach and transfer it to a bowl of ice water to stop the cooking. Let it sit for 2 minutes, then drain again.
Squeeze out the excess water from the spinach and place it in a mixing bowl.
Add soy sauce, sesame oil, garlic, sesame seeds, and a pinch of salt. Use your hands or tongs to toss everything together until well coated.
Taste and adjust seasoning if needed. Serve chilled or at room temperature.