Season the chicken (or fish) on both sides. In a shallow bowl, combine the flour, garlic powder (or granulated garlic) and paprika. Roll the butter in the flour and reserve.
Beat the eggs with the cheese and juice of 1/2 lemon.
In a large nonstick skillet, heat the oil, four turns of the pan, over medium to medium-high heat. Dredge two pieces of the chicken (or fish) in the flour, then coat in the egg batter and saute until golden, 2 to 3 minutes per side. Transfer to a plate; repeat.
Add the minced garlic to the pan. Stir for 1 minute, then deglaze with the wine (or stock). Add the flour-coated butter; whisk to form a sauce.
Place the chicken (or fish) on toasted bun bottoms. Cut the remaining 1/2 lemon into wedges and squeeze over top. Add the sauce, arugula, tomato, onion and bun top
