Yet if you were to tell your dinner guests that you were serving whipped tuna and anchovies as part of an appetizer, some of them might be tempted to say, "Can we just move onto the entree?"
Although there are endless variations on tonnato, every recipe I've seen includes tuna, anchovies, capers, olive oil and some type of acid, either lemon juice and vinegar.
At Oliveto, the restaurant where I work in Oakland, Chef Paul Canales makes a silky smooth tonnato by blending the basic ingredients with trickles of cream and olive oil.

At a recent dinner, we served it with sugar snap peas, cauliflower and other vegetables.
There are other interpretations. Vintage recipes call for whipped hard-boiled eggs in a tonnato, whereas some modern recipes include mayonnaise (homemade only, please). Jacques Pepin adds a little Dijon mustard to his tonnato, a French corruption that would likely spark riots in Italy.
Whatever the combination, your goal is to create a glistening sauce that is rich with the flavor of tuna, seasoned by background notes of capers and anchovy.

My version has a more rustic texture than what is served at Oliveto, but it is similar in taste and execution. You can see how I served the sauce with some vegetables from my garden, including squash, green beans and tomato.
Feel free to put your own twist on this dish and accompany it with a variety of vegetables or meats, such as chicken or turkey. But try not to skimp on the basic ingredients. High-quality tuna (or canned tuna), anchovies, capers and olive oil are essential.
Dijon mustard? Only if you want to trigger a riot.
Tonnato with Summer Vegetables
Serves: 6-8 appetizer-size portions
Ingredients:
12 ounces of fresh ahi tuna (or canned tuna)
6 anchovy fillets, rinsed and dried
1/4 cup olive oil or more
1/2 cup cream or an equal amount of milk and unsalted butter at room temperature
3 tablespoons capers
1 tablespoon lemon juice
Vegetables of your choice
Salt and pepper
Preparation:
1. Cut up and cook your vegetables, either by steaming or blanching. Try to include some that remain crunchy, like string beans or carrots and cook them in separate batches until just tender. Plunge in an ice bath and drain.
2. If using fresh tuna, add oil and tuna steaks to a skillet and heat until just barely bubbling. Maintain that gentle heat, turning once or twice until tuna is just cooked through. Do not overcook.
3. Add tuna and oil (or canned tuna) to blender or food processor. Add other ingredients, except for vegetables, and blend until smooth. Add additional cream or milk if mixture is too thick. [edited for clarity]
4. Your final sauce should be smooth enough to barely pour, without being runny. If still too thick, add more olive oil. (Go on. Just add it. It's good for you.)
5. After checking for seasoning, pour or spoon your tonnato onto a plate, arrange your vegetables in an artistic fashion and serve.
Note: Tonatto can be made in advance and refrigerated for a day or two. The flavors will meld and enrich the sauce. Bring to room temperature and rewhip before serving.