Combine the water, rice vinegar, sugar, and salt and stir until the sugar dissolves.

Add the daikon, carrots, and cucumbers to a large mason jar.

Pour the pickling liquid over veggies, screw on the lid, and allow the vegetables to pickle in the refrigerator for at least one hour and up to 24 hours in advance.

Combine the garlic, fish sauce, soy sauce, sugar, mayo, lime zest, and sriracha (if using) in a medium bowl.

Add the chicken, cover, and allow to marinate for at least 20 minutes or up to 24 hours.

Cook the chicken on an indoor grill or a skillet until cooked through.

Allow chicken to rest for 5 minutes before slicing thinly on the bias.

Toast the baguettes if desired, spread mayonnaise on bread, and top with chicken slices, pickled vegetables, cilantro leaves, and jalapeño slices.

Serve warm.