Quick-Marinated Skirt Steak with Sriracha Potatoes and Spinach

Place a rimmed baking sheet in oven and preheat oven to 450 °F. In a large bowl, toss potatoes with 1 tablespoon oil, 1/2 teaspoon salt, and 1/4 teaspoon pepper. Spread in a single layer on pre-heated baking sheet, and roast until golden brown and tender, tossing halfway through, about 20 minutes. In a medium bowl, whisk together 2 tablespoons oil, 1/4 cup soy sauce, chile paste, and 1/4 teaspoon each salt and pepper. Add steaks, turning to coat them in the marinade, and let stand at room temperature for 5 minutes. Meanwhile, heat a large cast-iron skillet over medium-high heat. Add 2 tablespoons oil and let oil heat briefly. Working in batches if necessary, sear steaks until medium rare, 3 to 4 minutes per side. Remove steaks from skillet and transfer to a cutting board or plate to rest, reserving skillet. Add broth and remaining 1 tablespoon soy sauce to skillet over medium-high heat, scraping bottom of skillet to deglaze the pan. Add spinach to the skillet and cover; cook until wilted, about 3 minutes. In a medium bowl, mix mayonnaise and sriracha. Divide spinach among four plates and top with steak; serve potatoes alongside, drizzled with sriracha mayo and garnished with bonito flakes, if desired.