Over medium heat, toast the mustard seeds in a large saucepan. Cook until fragrant, about 2 minutes.
Add the water, vinegar, sugar, garlic, habaneros, red pepper flakes, and salt to the pot. Simmer for 10 minutes.
While simmering, cut your cucumbers in your desired shape. Make sure spears fit inside the jar (cut off an end if not).
Remove from the heat. Add the cucumbers and dill to the liquid and let cool to room temperature, approximately 1 hour. (If you want crunchier pickles, let the liquid cool BEFORE adding the pickles so the heat does not cook them).
Put the pickles and brine in mason jars or another seal-able container, making sure the pickles are submerged. Keep chilled, ideally for at least 10 hours before eating. Pickles can last up to two weeks.
This made enough to fill three pint sized mason jars.Try to find cucumbers that are just long enough to fit in the jar. But if they are too long, you can chop off one of the ends for them to fit as spears.Add more pickles to the same brine to keep the pickle supply going! You may need to add more garlic or habanero to lift the flavors as time goes on.