In a saucepan, combine the vinegar, water, salt, peppercorns, mustard, sugar and bay leaf. Bring to a boil over high heat. Reduce heat to low and simmer for 10 minutes. Remove from heat and let cool slightly while you prepare the vegetables.
Slice the cucumber into ½” thick slices. Slice the jalapeno, removing the ribs and seeds if you would like them less spicy. Peel and thinly slice the garlic. Slice the green onions.
Tightly pack the cucumbers, jalapenos, garlic, and dill sprigs in jars.
Add the cooled brine to the jars, being sure that the vegetables are completely submerged.
Cover and refrigerate for at least an hour, for the best flavor, let sit overnight.
Notes
The pickles can be used for up to 2 months. Just keep them in a sealed jar in the fridge to keep them tasting crisp and fresh.