Heat a wok over medium-high heat. Add 1 tablespoon vegetable oil and swirl to coat. Season steak with salt and add to wok. Cook, stirring, until beef is golden brown on both sides, about 2 minutes. Transfer to a medium bowl and set aside.
Add another tablespoon vegetable oil to the wok and swirl to coat. Add garlic, ginger, scallions, chile sauce, sugar snap peas, and 1 pound thinly sliced Swiss chard stems (remove and tear leaves into 2-inch pieces and reserve). Cook, stirring constantly, until snap peas are bright green and crisp, about 2 to 3 minutes. Transfer to bowl with beef.
Add another tablespoon oil to wok and swirl to coat. Add half of the Swiss chard leaves and cook, stirring, until wilted, about 1 minute. Transfer to bowl with beef and snap peas. Repeat with remaining tablespoon oil and chard.
Return everything to wok, heat briefly, and season with salt. Squeeze with lime juice, toss to coat, and serve immediately.
Extra credit: Have your ingredients prepped and ready before you start cooking -- stir-fry moves fast! And avoid overcooking by putting too many things in the wok at once, which will steam rather than stir-fry the vegetables. Variations: Tofu, shiitake mushrooms, cabbage, and hot peppers; ground chicken, bok choy, tomatoes, and roasted cashews.