Into a pot over medium heat, add 1 cup of cubed butter.
Heat on medium until melted. Once it's melted, keep stirring it until the milk solids separate and start to toast. Once brown and nutty, remove from heat and allow to cool. The deeper the colour the deeper the toasted nutty flavours. Remove from heat.
With a sharp knife, mince 1 shallot. We want this to be as fine as possible to go over it a few times.
Add your shallots to the brown butter (if your butter is still hot, it might bubble up so watch out!). Next add 1 tbsp of dijon mustard, 2 tbsp of maple syrup. Give that a good whisk so the maple syrup and dijon are fully emulsified.
Lastly, stream in about 3 tbsp of apple cider vinegar. Give it a good whisky until it’s fully emulsified.
Store in an airtight container in the fridge for up to 1 week.
