Unlike other species of pufferfish, the flesh of the Northern pufferfish is not poisonous and needs no special handling. They are best cooked pan-fried or seared, either with a spice rub or just salt and pepper.
Looking for more ideas, check out this EATER article about blowfish tails showing up on menus in Washington, DC and New York.
SAFE HANDLING — Keep frozen until ready to use. Remove from packaging and defrost in the refrigerator 8-10 hours before use. Do not defrost at room temperature. Once defrosted, do not refreeze and use within 3 days.