In a blender, add cold soy milk, vinegar, salt, mustard powder and garlic powder. Grind it at low setting for 3 minutes. Now gradually add olive oil to it while it continues to blend.
Blend it at a low setting until a thicker consistency is achieved.
Once done, place it in a glass jar or bowl and keep it in the refrigerator. Fresh soy mayonnaise is ready for sandwiches, and salads. It will stay fresh for one week when stored in refrigerator.