Preheat your grill to the highest setting. Take the steak out of the fridge for at least 30 minutes to take the chill off.
In a bowl, whisk together the brown sugar, ground coffee, smoked paprika, salt, pepper and ground mustard. Rub it all over both sides of the steak.
Place the steak on the grill grates and cook for 5 minutes, then flip and cook for 3 to 5 minutes more. I like to cook mine until they reach an internal temperature of 140 degrees F. Remove the steaks and let them rest for 10 to 15 minutes before slicing.
Place the corn directly on grill grates. You can do this while the steak is cooking too! Grill for 10 minutes, rotating the corn every other minute. Remove it from the grill and let it cool slightly. Once cool, slice the kernels off the cob.
In a bowl, stir together the corn, herbs, onion, peppers, lime juice, and a pinch of salt and pepper. Toss a few times to combine it well.
Slice the steak against the grain. Top it with the corn salsa and serve!