Add the black sesame seeds and white sesame seeds to a 26 cm heavy based pan and mix well on low heat. Sesame seeds burn easily, so shake the pan often to toss the seeds, so they cook evenly.At first, shake every 15 seconds and as the pan heats up, every 5 seconds until the white sesame seeds are golden. Transfer to a plate to cool. Do not leave sesame seeds in the pan or they will not cool down quickly enough.
Once the sesame seeds are cool, put them in the blender or food processor to crush them using a dry material dedicated blade. Transfer to a small bowl.Crushed black sesame seeds are sticky and cannot be used directly to flavor the noodles; they must be diluted first. If diluted with all water, the taste will be reduced, and if diluted with oil, the sauce will be too greasy.A combination of both gives a good result. Slowly pour in the sesame oil, while stirring, scraping the sides as you go.
Once combined, slowly pour in the hot water while stirring to ensure uniform texture.
Once the sesame sauce can flow in a straight line, it is the right consistency to add to the noodles.
Finally, add the salt and stir well. Salt balances the greasy taste of sesame oil while bringing the taste to a new level. Smell the aroma of that sauce! It just doesn’t compare to store bought sesame sauce.