A Dublin deli-style Irish chicken fillet roll made at home: shallow-fried crispy chicken cutlets in a soft buttered roll with shredded lettuce and a simple garlicky mayo (with optional hot sauce).
Prep the chicken fillets: Lay each chicken breast flat and carefully slice horizontally through the thickest side to create 2 even fillets from each breast (4 thinner pieces total).
Marinate in buttermilk: In a medium bowl, whisk together buttermilk, grated garlic, 1/2 tsp salt, 1/4 tsp pepper, paprika, and garlic powder (if using). Add chicken, turn to coat, cover, and let sit 20–30 minutes at room temperature (or up to 4 hours in the fridge).
Make the garlicky mayo: In a small bowl, stir together mayonnaise, finely grated garlic, 1 tsp lemon juice, a pinch of salt, and pepper. Taste and adjust; if making it spicy, divide and stir hot sauce into some or all of the mayo. Chill until needed.
Prep the rolls and lettuce: Finely shred the lettuce. Split rolls lengthwise; optionally toast cut sides 1–2 minutes until barely golden. Butter the insides generously and set aside.
Set up the coating station: In a shallow dish, mix flour, panko, 1/2 tsp salt, and 1/4 tsp pepper. Remove chicken from the buttermilk, letting excess drip off.
Coat the chicken: Press each fillet into the flour–breadcrumb mixture on both sides, pressing firmly so crumbs adhere evenly. Shake off loose flour and place on a rack or plate.
Heat the oil: Add neutral oil to a large frying pan to a depth of about 0.5–1 cm (1/4–1/3 inch). Heat over medium until a pinch of coating sizzles steadily (about 170–180°C / 340–355°F if using a thermometer).
Fry the chicken: Fry 2 fillets at a time for 3–4 minutes per side until crisp and golden and the chicken reaches 75°C / 167°F in the center. Drain on paper towels and repeat, adjusting heat if browning too quickly.
Rest and slice: Rest fried chicken 3–5 minutes. Slice into strips if desired for easier eating, or leave whole.
Assemble the rolls: Spread garlicky mayo on the buttered rolls, add shredded lettuce, then top with hot chicken fillets. Add optional cheddar, tomato, and/or red onion. Close gently.
Serve right away while the chicken is hot and crisp; serve extra mayo on the side for dipping if desired.