Rinse the beef tongue under cold water
Trim off any excess fat or debris
Place the tongue in a large pot
Cover with water
Add salt, onion, garlic, bay leaves, and peppercorns if desired
Bring to a boil
Reduce to a simmer
Skim off any foam
Cook until tender, about 2.5 to 4 hours
Check tenderness by piercing with a fork
Remove the tongue from the pot
Let it cool slightly
Peel off the outer skin while still warm
Trim away any tough or discolored parts
Slice or chop the tongue as desired
Serve plain, seared, or in tacos, sandwiches, or stews