1/2 Cup black mustard seeds
2/3 Cup yellow mustard seeds
Scant 1 Cup apple cider vinegar
1 Cup beer
3 habañero peppers ribs and seeds removed, chopped (For more heat, you can leave some seeds in.) (If using dried, be sure to rehydrate them by soaking in water overnight.)
2-3 Tbsp honey
Salt to taste
Add both types of mustard seeds to a mixing bowl. Pour in vinegar and beer, stir to combine. Cover bowl 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 habañero peppers, honey and salt. Process/blend to desired consistency.
If mustard is too thick, add a little of the reserved liquid, a little at a time, until mixture reaches a consistency you like.
Transfer mustard to mason jars or other airtight containers and store in the refrigerator. Flavors will deepen and develop more over time.