In a mixing bowl, combine the minced lemongrass, garlic, fish sauce, soy sauce, and brown sugar to create the marinade.

Add the thinly sliced beef to the marinade, tossing to coat thoroughly, and let it sit for at least 15 minutes while you prepare the other components.

Cook the jasmine rice according to package instructions until fluffy and tender.

While the rice cooks, whisk together the rice vinegar and a pinch of sugar in a small bowl, then add the julienned carrots and sliced cucumber to quick-pickle for 10 minutes.

In a separate small bowl, mix the mayonnaise and sriracha sauce until smooth to create the spicy drizzle.

Heat a large skillet or grill pan over medium-high heat with a drizzle of oil.

Add the marinated beef in a single layer (working in batches if necessary) and sear for 2-3 minutes per side until browned and caramelized at the edges.

Drain the pickled vegetables and discard the excess liquid.

Assemble the bowls by placing a base of warm rice, then topping with the grilled beef, pickled carrots and cucumbers, and fresh cilantro.

Drizzle generously with the sriracha mayo and serve immediately with a lime wedge on the side.