Preheat the oven to 200°F. Line a baking sheet with aluminium foil.
While the oven heats, prepare the tartar sauce. In a small bowl, stir together the mayonnaise, red onion, pickle relish, parsley, capers, and lemon juice. Cover with plastic wrap and refrigerate until ready to use.
In a small bowl, stir together the mayonnaise, red onion, pickle relish, parsley, capers, and lemon juice.
Spread the flour on a large piece of parchment paper. In a shallow bowl, beat the eggs. Spread the breadcrumbs on another large piece of parchment paper.
Season the tilapia fillets with salt and pepper.
Dip a fillet first in flour to coat, shaking off the excess. Dip in the egg and then place into the breadcrumbs to coat, pressing to help the coating adhere.
Using a fork, lift the fish from the breadcrumbs and roll it in the crumbs to coat the other side.
Pour the oil into a large, heavy ovenproof skillet until it registers about 1-3/4″ deep. Heat the skillet over medium-high heat until a small drop of batter sizzles and deep-fries when dropped in.
Add the fish in batches and cook until golden brown on all sides, 3-5 minutes.
Transfer the fish to a baking sheet and keep warm in a 200-degree oven.
Serving Suggestions: Serve the fish with the tartar sauce on the side. Serve immediately with lemon wedges too.