Place water, mustard, vinegar, salt, turmeric & garlic powder in a small saucepan (before you turn on heat) & whisk until smooth.
Take ¼ cup of the mixture & place in a separate small bowl. Whisk in the white flour ensuring it is 100% smooth. If it is not smooth, pass through a cheesecloth. Once smooth, add this back into the saucepan & whisk to combine.
Turn saucepan onto medium-low heat.
Stir frequently, scraping sides & bottom.
Bring mixture to a boil, then reduce heat to a simmer until slightly thickened (about 5 minutes) stirring very frequently. It may coagulate in the bottom corners, make sure you scrape them out so they don't burn.
Once mustard coats the back of your spatula, take it off the heat. Allow to cool for a few minutes in the pan before transferring to a container with plastic wrap on the surface of the mustard (to prevent skin forming), then place into the fridge for 30 minutes to cool.
Transfer to an airtight container & allow flavours to meld & intensify overnight minimum 24 hours.
Store in the refrigerator for up to a month.
