Pat one 12-oz. New York strip steak (about 1″ thick) dry with paper towels. Season generously all over with kosher salt. Let sit 10 minutes.
Meanwhile, squeeze juice from 2 limes into a medium bowl; discard limes. Add 4 garlic cloves, finely grated, ½ cup peanut butter, ¼ cup soy sauce, 2 Tbsp. fish sauce, 2 Tbsp. pure maple syrup, and 2 Tbsp. water and whisk to combine. (It will take a few minutes to emulsify into a smooth sauce.) Set peanut sauce aside.
Place 1 medium carrot, peeled, thinly sliced into 3″–4″-long matchsticks, and 1 Persian cucumber, thinly sliced, in a small bowl and squeeze juice from remaining 1 lime over; discard lime. Toss to combine. Set carrot mixture aside.
Heat a dry large skillet, preferably cast iron, over medium-high. Pat steak dry again (the salt will have drawn out more moisture). Rub all over with 1 Tbsp. vegetable oil. Cook steak, undisturbed, until a deep golden crust forms, 4–5 minutes. Turn over; cook until browned on other side and an instant-read thermometer inserted into thickest part registers 120° for medium-rare, about 5 minutes. Using tongs, stand steak up on an edge and cook until browned, about 1 minute. Repeat on remaining edges. Transfer to a cutting board; let rest 10 minutes.
Meanwhile, place 1 lb. dried wide rice noodles in a large pot of boiling water and stir to separate; remove pot from heat. Let noodles sit until cooked through, 8–10 minutes. Drain in a colander and rinse under cold running water to stop the cooking.
Thinly slice steak against the grain. Divide reserved peanut sauce among shallow bowls and arrange noodles over. Top with steak slices and reserved carrot mixture, then 1 cup mixed tender herbs (such as mint, basil, and/or cilantro).