CAUTION: Be super careful not to touch the liquid during the cooking process! Do NOT lick the spoon. It's wicked hot and can burn you. I know it's tempting but don't do it!! Seriously! Use common sense, people!
Place a rimmed baking sheet or baking pan aside for later.
In a large glass measuring cup, or microwave safe container, combine sugar and corn syrup. Stir with a spoon.
Place the measuring cup in the microwave and cook for 4 minutes. The mixture is going to get extremely hot so don't touch the mixture by accident, or on purpose. Use your noggins, peeps.
Remove the measuring cup from the microwave and add the shelled pistachios to the measuring cup and microwave on high heat for 3 minutes. Do NOT touch the mixture, it's flipping hot!
Remove the measuring cup from the microwave and add butter and vanilla, it may bubble up, it's okay, just stir with a heatproof spatula until well combined. Place back in the microwave and cook on high for 1 minute. Again, do not touch it, this stuff is piping hot.
Add the baking soda to the measuring cup and mix for about 20 to 30 seconds while the foaming slows down. Once it's all settled you can pour it onto a prepared baking sheet, or large pan. Smooth out with a scraper or the back of a spoon. I spray the back of a spoon with nonstick spray then smooth mine out that way. If desired you can toss some demerara sugar over top of the surface. Allow the candy to cool completely.
Break into pieces by hand or use a toffee hammer. You can eat it right away or store it in airtight container.
Serve with a big old candy loving smile!