fifteen 8-inch skewers, soaked for at least 2 hours and up to overnight
For the marinade: Combine the soy sauce, brown sugar, ginger, lime juice and chile-garlic sauce in a saucepan over medium-low heat. Bring to a simmer and cook, stirring occasionally, for 10 minutes. Let cool.
Loosely thread the skirt steak strips onto the soaked skewers and place them in a deep pan. Top with the marinade. Cover and refrigerate for at least 2 hours.
For the chile-herb sauce: Combine the cilantro, parsley, mint, garlic, green onions and Thai chiles in a food processor and pulse until coarsely chopped, scraping down the bowl as needed. Add the fish sauce, sugar, lime juice, 1 teaspoon salt and 1/2 teaspoon pepper and pulse until combined. With the machine running, drizzle in oil; pulse for another 15 seconds. Add the mayonnaise and pulse to combine. Transfer to a bowl, cover and chill until ready to serve.
For cooking the steak: Prepare a grill for medium-high heat. Grill the steak for 2 to 3 minutes per side. Transfer to a plate and let rest. Serve with the chile-herb sauce on the side.