Start by peeling the daikon and carrots and cutting both into large matchsticks along with the English cucumber.  Slice the jalapenos as well.  Deseed them if you prefer to limit the spice.  

Heat rice wine vinegar, sugar, and kosher salt in a small sauce pan over medium heat.  Stir so sugar is dissolved and bring to a simmer.

While the pickling liquid comes to a simmer, fit the cut vegetables into one extra large mason jar very tightly.  

Once the liquid comes to a simmer, pour the hot liquid over the vegetables in the mason jar.  

Let cool with the lid off for at least 30 minutes, then close the lid and store in the refrigerator for up to 2 months.