For a quick, easy, and delicious meal, make this salad for supper in under 30 minutes.
In a small bowl, whisk together lime juice, 1/4 cup vegetable oil, fish sauce, and sugar until sugar dissolves; set aside.
Season steak with salt and pepper. In a large, heavy skillet, heat 1 tablespoon oil over high. Cook steak, 3 to 4 minutes per side for medium, flipping once. Tent with foil on a cutting board. Let rest 5 minutes.
Meanwhile, in a large bowl, toss together lettuce, carrots, cucumber, tomatoes, mint, peanuts, and chile. Drizzle with dressing and toss again. Thinly slice steak against the grain and serve on salad.