This vinegar-based tuna salad is far from the mayonnaise-centric rendition of deli counters and cafeterias. First, you'll marinate chickpeas in oil and vinegar to infuse them with flavor. These join oil-packed tuna, radicchio, and red onion, plus kalamata olives and capers. These last two flavor bombs cut through the richness of the tuna and mellow out the bold lettuce. The result is sophisticated, delicious, and a revolution in the possibilities for canned tuna.