1. Grind the whole mustard seeds for a few seconds in a spice or coffee grinder or mortar and pestle. I used the latter because mostly whole seeds would add a pleasing crunch to the mustard.

2. Pour the semi-ground seeds into a non-reactive bowl and add the salt and mustard powder. I stirred this dry mixture with a very small whisk to be sure to eliminate any lumps before I added the liquids.

3. Pour in the wine. Stir well. Wait five or ten minutes, then add the vinegar. Stir well again.

3a. Stop here and refrigerate the mustard for 24-48 in order to taste test the mustard before adding the fruit. Bitterness is a byproduct of the mustard reaction. You’ll be able to detect its presence immediately. However, the bitterness fades after a day or so. By the way, the product at the end of step 3 looks like mustard soup. After it ages for a day, it will be a thick, creamy. I promise!

4. Buzz the peaches and mango with a regular or an immersion blender. You should get about 1 1/2 cups fruit puree. Add puree, along with lime juice, to mustard.

5. Pour or spoon into a glass jars. Wait at least 12 more hours before using. Mustard made this way will last several months in the fridge.

Note: Making mustard can be a bit like buying a cat in a sack—you can’t predict the outcome until you’ve completed the recipe. Here are some ways to rescue a mustard that has run amok.
After three or four days, mustard is still too hot for your taste?
Either microwave it for a few seconds or add a few drops of lime juice.
Adding fruit changed your spreadable mustard into a dipping sauce?
Add a bit of almond flour. To make flour, grind almond slivers in a spice or coffee grinder.