Mix together the tomatoes, onion, garlic, vinegar, feta, and 1/4 of the olive oil in a bowl and set aside.
Place breadcrumbs on a dish and press the chicken into the breadcrumbs to coat both sides well.
Heat a nonstick pan over medium heat with the remaining oil.
Add the chicken to the pan and cook on both sides till golden brown and an internal temperature of 160 degrees is achieved using a thermometer. Place on a paper towel lined plate to drain excess oil.
Lightly toast the bread. Drizzle each half with oil.
Layer the roll with basil, chicken, and top with the tomato mixture, cut in half, and serve with chips and pickles.