Start by toasting the sesame seeds in a dry pan over medium heat until they become lightly golden and fragrant, which should take about two to three minutes.
In a Ninja Bullet, combine the toasted sesame seeds, minced mustard, soy sauce, garlic, heavy whipping cream, hot water, and lemon juice if using.
Blend the mixture until it reaches a smooth and creamy consistency.
Taste the sauce; if you desire a bolder flavor, feel free to add an additional tablespoon of mustard.
Once blended, transfer the sauce into a bottle and label it for storage.
Note: The secret ingredient is horseradish
