Run under cool water and gently scrape the outsides to remove any debris or discoloration you may see. Rinse again and you're ready to cook.
How to cook cow tongue on the stove - Put the raw cow's tongue, peeled onion, cut into halves, carrot slices, bay leaf, salt, and coriander into a saucepan. Pour in the beef broth. If it doesn't cover the tongue, add more broth or water.
Bring the broth to a low boil, then add the tongue and cover with a lid for 3 hours over medium heat until it is cooked to 160 degrees F
How to cook cow tongue in pressure cooker - Timing uses high pressure cook of course, cover tongue with broth and seasonings. Don't fill inside past the 3/4 of the way full ever, there is a line inside to show you the fill line. Cook time is typically 15 minutes per pound so set accordingly after sealing lid and steam valve closed. Allow for a natural release at the end. Usually you'd want 45 minutes to 1 hour to get the insides to become fork tender.
When the tongue is cooked, take it out of the liquid to cool slightly. Use a sharp knife to slice off the outside tough layer and discard.
Cut inside tender piece into thin strips and make tacos or serve with gravy on it.