Preheat oven to 400° F.
Smash chickpeas in bowl until completely mashed.
Add tuna, mustard, mayo, parsley, onion, relish, cayenne, garlic, and juice from 2 lemon wedges. Mix well. Add salt and pepper to taste.
Mix in flour until thick enough to form small patties that are 2–3 inches in diameter and ½ inch thick.
Chill in fridge for 5–10 minutes.
Preheat large pan over medium heat.
Add oil to pan and heat for 30 seconds, then add fritters to pan.
Flip fritters once golden brown. Repeat process on other side. Remove from pan.
Serve with tartar sauce.