Heat 1 Tbsp. extra-virgin olive oil in a large skillet, preferably cast-iron, over medium-high. Add 1 lb. green beans, trimmed, sprinkle with 1 tsp. Diamond Crystal or ½ tsp. Morton kosher salt, and season with pepper. Cook, tossing occasionally, until bright green and charred in spots but still crisp-tender, 5–7 minutes. Transfer to a large plate. Repeat process with remaining 1 lb. green beans, trimmed, 1 Tbsp. extra-virgin olive oil, 1 tsp. Diamond Crystal or ½ tsp. Morton kosher salt, and more pepper. Remove from heat and return all of the green beans to skillet (if they don’t fit, use a large bowl instead). Add reserved vinaigrette and toss to coat.
