Recipe adapted from Tom Colicchio.
Sprinkle sugar over coriander and fennel seeds; roughly chop (or process spices in a spice grinder and add sugar in next step). Transfer to a small bowl with shallot, jalapeno, cilantro, and garlic. Pat steak dry and rub all over with spice mixture.
Heat a grill to high. Clean and lightly oil hot grill. Season steaks all over with salt and pepper. Grill steaks, 8 minutes per side for medium-rare, flipping once. Transfer steaks to a plate and let rest 10 minutes. Thinly slice against the grain and serve with steak sauce, horseradish sauce, or chimichurri.