In a medium bowl, toss the julienned carrots and daikon radish with the rice vinegar and a pinch of salt. Let sit for at least 15 minutes to quickly pickle while you prepare the rest of the ingredients.

In a separate bowl, whisk together the soy sauce, fish sauce, minced lemongrass, minced garlic, and brown sugar until the sugar is mostly dissolved.

Add the thinly sliced turkey breast cutlets to the marinade and toss to coat evenly, ensuring the lemongrass and garlic adhere to the meat.

Heat the vegetable oil in a large skillet over medium-high heat. Once the oil is shimmering, add the marinated turkey slices in a single layer.

Sear the turkey for 3 to 4 minutes per side, or until fully cooked through and the edges are beautifully caramelized and golden brown. Remove from the heat.

Assemble the sandwiches by spreading a generous layer of mayonnaise on the inside of each toasted baguette, then layer the warm lemongrass turkey evenly among the breads.

Top the turkey with the drained pickled carrots and daikon, fresh cilantro sprigs, and jalapeño slices. Serve immediately with extra hot sauce on the side if desired.