Add both types of mustard seeds to a mixing bowl. Pour in vinegar and beer, stir to combine. Cover with plastic wrap and let sit on the counter for 12-15 hours.

Scoop out about 1/3 of a cup of the liquid off the top and reserve.

Pour the rest of the contents into a food processor or blender and add habanero peppers, honey and salt.

Process to desired smoothness.

If mustard is too thick, add in reserved liquids a little at a time until it reaches a consistency you like.

Pour mustard into mason jars or other airtight containers and store in the refrigerator.

Flavors will deepen and develop more over time.