Roast Tuna
from Around the Roman Table: Food and Feasting in Ancient Rome by Patrick Faas

"Ius in cordula assa: piper, ligustcum, mentam, cepam, aceti modicum et oleum."

"Sauce for roast tuna: pepper, lovage, mint, onion, a little vinegar, and oil." (Apicius, 435)

for the vinaigrette
3 tablespoons strong vinegar
2 tablespoons garum, or vinegar with anchovy paste
9 tablespoons olive oil
4 finely chopped shallots
1 teaspoon pepper
1 teaspoon lovage seeds
25g fresh mint

Put all of the vinaigrette ingredients into a jar and shake well to blend them together.

Brush your tuna fillets with oil, pepper and salt, then grill them on one side over a hot barbecue. Turn them and brush the roasted side with the vinaigrette. Repeat. The tuna flesh should be pink inside so don't let it overcook. Serve with the remains of the vinaigrette.