Step 1Prepare a charcoal grill for direct, high-heat grilling or heat a gas grill to high. (Alternatively, heat a large cast iron skillet over high heat.) Season the steak all over with salt and add to the grill or pan. Cook, flipping once halfway through, until golden brown and an instant-read thermometer inserted in the thickest part reads 120 to 125 degrees for medium-rare doneness. Transfer the steak to a plate, tent loosely with foil and let rest for 5 minutes while you make the spice mixture. Leave the grill on.
Step 2Combine the Sichuan and black peppercorns and coriander and cumin seeds in a mortar and pestle or spice grinder and finely grind. Transfer the steak to a cutting board and cut across the grain into ¼-inch-thick slices.
Step 3Heat the oil in a large cast iron pan or skillet over high heat on the grill (or on your stove). Add the garlic and cook, stirring, until fragrant, 20 to 30 seconds. Add the red chiles and reserved spice mixture and cook, stirring constantly, until lightly toasted, 1 to 2 minutes. Add the sliced steak, and toss quickly to combine with the spices (you don’t want to cook the steak), about 10 seconds. Season with more salt.
Step 4Immediately transfer the steak and spices to a large serving bowl or platter. Sprinkle with the sliced scallions, squeeze the citrus wedge all over and serve immediately.
Sichuan Chicken-fried Steak
Whisk 2 large eggs in a bowl, place 1 ½ cups all-purpose flour in a second bowl and 2 cups panko breadcrumbs in a third bowl. Slice the raw hanger steak into ¼-inch-thick slices and season with salt and pepper. Dredge the slices first in flour, next in egg, and then in breadcrumbs, shaking off any excess. Heat 2 quarts peanut oil in a large Dutch oven or deep-fryer until it registers 350 degrees on a deep-fry thermometer. Working in batches, add the steak slices and fry until golden brown and just cooked through, 2 to 3 minutes. Transfer the fried steak to paper towels to drain briefly, then toss in a bowl with the Sichuan spice mixture and scallions. Serve with the calamansi or lemon wedge.