Dice red onion and place in a small bowl with red wine vinegar. Set aside.
Soak currants in boiling water in another small bowl for about 15 minutes. Drain. If using raisins, chop them into smaller pieces.
Zest and juice lemon. Mince 3 Tablespoons parsley leaves and dice celery. Dice fennel bulb. Toast pine nuts.
Put chicken in a bowl and add 1 teaspoon lemon zest, 2 Tablespoons lemon juice, parsley, celery, diced fennel, pine nuts, mayonnaise, ground fennel seeds, and cinnamon. Add in soaked onions (leave the vinegar behind), and taste. Add salt and more vinegar if desired.
*If you're short on time, purchase a rotisserie chicken from the store. Alternatively, bake 2 pounds of boneless skinless chicken thighs at 375 for 20-25 minutes, or until no longer pink in the middle. Be sure to season with 2 teaspoons of fine sea salt and freshly ground black pepper before cooking.**If you're not a fan of mayonnaise, use 3/4 cup plain yogurt mixed with 2 Tablespoons extra virgin olive oil as a substitute, or omit altogether.