To blanch the green beans: Bring a large pot of salted water to a boil and prepare an ice bath. Blanch the green beans until just tender, 3-4 minutes. Transfer to the ice bath. Once cool, drain the green beans, pat dry, and toss with the sunflower oil.
To make the chile-soy sauce: Place the sambal oelek, soy sauce, garlic, brown sugar, and 2 tablespoons of the crispy onions in a medium bowl. Stir to combine and set aside.
To char the green beans: Preheat a pizza oven, grill, or broiler to medium-high heat along with a medium heat-safe skillet (preferably cast iron). Once hot, carefully place the green beans in the preheated skillet. Return to the heat and cook until the green beans are lightly charred—this should only take a minute or two, depending on your heat source.
To serve: Immediately transfer the green beans to the bowl with the sauce. Toss to coat and let cool slightly, tossing occasionally. Transfer to a small serving platter and finish with the remaining crispy onions.