Pat the Beef Sirloin Steak dry and season both sides lightly with Sea salt; heat a skillet with a little Neutral cooking oil over high heat until shimmering and sear the steak 2–4 minutes per side (depending on thickness) until browned and cooked to your liking.
Transfer the steak to a cutting board, tent with foil and rest for 5–10 minutes to allow the juices to redistribute, then thinly slice against the grain.
While the steak rests, thinly slice the Shallots, halve the Cherry tomatoes, peel and slice the Cucumber into coins (or half-moons), and cut the Spring onions into 1-inch pieces on the diagonal.
Pick and roughly chop the Fresh mint leaves and Fresh cilantro leaves, keeping some whole leaves for garnish if you like.
Make the dressing by squeezing the juice of the Limes into a bowl, then add Fish sauce and a little grated or smashed Palm sugar; finely mince the Thai bird's eye chilies and the Garlic clove and stir them in—adjust the balance of sour, salty and sweet to taste.
Combine the sliced steak with the prepared vegetables and herbs in a large bowl, then pour the dressing over and toss gently to coat everything evenly.
Taste and adjust seasoning with extra Fish sauce or Limes if needed, garnish with remaining mint and cilantro, and serve the salad immediately while the beef is still warm.
