Increase the heat to medium-high and add olive oil, maple syrup, soy sauce, pepper, and red pepper flakes (if using). Give it a stir to coat, spread out into an even layer, and let cook for 3-5 more minutes, undisturbed, or until nicely browned. Turn the heat down if it begins to burn. Give it a stir, spread out again, and cook for 1 more minute, undisturbed. Sprinkle on the salt and stir to coat.