Pat the flank steak dry with paper towel and place it in a large resealable bag. Add the smashed garlic and set aside.
In a small bowl place the ginger, fish sauce, soy sauce, palm sugar, sesame oil and the zest and juice of the lime. Whisk to combine and pour over the steak. Force the air out of the bag and seal. Transfer to the fridge and marinate for at least 2 hours or overnight.
When ready to eat, heat a charcoal grill or cast iron griddle over medium-high heat until smoking. Remove the steak from its marinade and add to the grill. Cook the steak 3-5 minutes a side or until medium rare. Take the steak off of the grill and tent with foil until ready to slice.
When ready to plate, slice the steak into thin slices against the grain. If your slice runs the entire length of the steak, feel free to slice it into thirds for easy eating.
Chili Lime Vinagrette
Place all ingredients in a bowl and whisk to combine. Transfer to the fridge and chill until ready to serve.
Thai Beef Salad
Place the napa cabbage, red cabbage, carrots, mango, shallots, sugar snap peas, oranges, bean sprouts and cilantro in a large bowl. Add the steak and toss until everything is well integrated.
Give the Vinaigrette a quick whisk and pour over the salad. Toss to coat. Sprinkle the peanuts, and mint leaves over top. Serve immediately.
*Substitute brown sugar for palm sugar if you don't have it.