Drain the tuna and place in a medium-sized mixing bowl.
In a food processor, pulse the sun-dried tomatoes, shallots, spinach, olives, capers, and pepper until roughly blended. Then add the red wine vinegar and olive oil and pulse until combined. Add the dressing to the tuna and toss until combined. Taste and adjust seasonings as needed. Add more olive oil if it looks dry.
Serve a scoop on lettuce or green salad, or make this into sandwiches.
Notes
If you buy the tuna in oil, you’ll still want to drain it, and add fresh extra-virgin olive oil, but you’ll want to start with 1 tablespoon. Also, I happen to love the mix of white and light tuna together, but you may have different feelings about what kind of tuna you prefer, and how you like it packed.
This tuna will keep for 4 days in the fridge. Also, know that if you store the tuna for a day or more it might dry out a bit as the tuna absorbs the dressing, so it might need a splash of olive oil to loosen it up. Or, if you want it tangier, even a splash of vinegar, too.