These tuna-stuffed peppers are ubiquitous in delis all over Susa, Italy.
- Select 24 whole peppers. (Refrigerate any remaining peppers in a jar, with brine to cover, for another use.) Cut off and discard the pepper stems. Scoop out the seeds with a small spoon (a measuring teaspoon works well). Rinse the peppers to remove any residual seeds, and set in a colander to drain.
- Combine tuna, lemon juice, oil, capers and anchovies (if using) in a medium bowl.
- Fill each pepper with about 1 teaspoon of the tuna mixture and place them on a serving plate. (Depending on the size of the peppers, you may not fill all 24.) Grind some pepper over the stuffed peppers.
- Bring vinegar to a boil in a very small saucepan and simmer until syrupy and reduced to about 2 teaspoons, 3 to 3 1/2 minutes. Drizzle the syrup over the peppers.