Either way. i susually use a grill unless I'm soing several.
They are sort of like 'roast beef', that is to say, one cooks them till med-rare or med internally, with a nice external finish.
They do not - technically - need to be low/slowed, but they do best, imo, if the are cooked gently till shy of one;s target then seared to finish. Rest, then slice thinly.