Pat chicken breasts dry. If breasts are thick, halve them horizontally or pound between plastic wrap to about 1/3 inch (8 mm) thickness using a meat mallet or rolling pin. Season both sides with 1 tsp kosher salt and 1/2 tsp black pepper.

Set up breading station

Place flour in a shallow dish. In a second dish, whisk eggs with 3 tablespoons milk until smooth. In a third dish, combine breadcrumbs, grated Parmesan, smoked paprika, garlic powder, onion powder, remaining 1/2 tsp kosher salt and 1/4 tsp black pepper; mix well.

Bread the chicken

Working one piece at a time: dredge chicken in flour, shaking off excess; dip into egg wash, letting excess drip; press firmly into breadcrumb mixture until evenly coated. Set on a wire rack and rest 5 minutes for coating to adhere.

Fry the schnitzel

Pour vegetable oil into a large skillet to a depth of about 1/4 inch and heat over medium-high until shimmering and a breadcrumb flake sizzles when added (about 350°F / moderate heat). Add schnitzels (do not overcrowd) and fry 3–4 minutes per side until golden brown and internal temperature reaches 165°F (74°C). Transfer to a paper towel–lined rack to drain; keep warm in a low oven (200°F / 95°C) if needed.

Hippie Greens & Pickled Onion

Quick-pickle the onion

Combine rice wine vinegar, water, sugar and 1/4 tsp salt in a small bowl; stir until sugar dissolves. Add thinly sliced red onion and let sit at room temperature for at least 10 minutes (longer for stronger flavor). Drain before assembling; reserve a spoonful of pickling liquid if you want to loosen the greens dressing.

Dress the greens

In a bowl toss the mixed baby greens and chopped dill with 1 tablespoon olive oil, 1 tablespoon lemon juice, and a pinch of salt and pepper. If greens seem dry, add 1 teaspoon of the reserved pickling liquid to brighten.

Lemon Caper Aioli

In a small bowl whisk together mayonnaise, chopped capers, lemon zest, lemon juice, minced garlic, Dijon, 1/2 tablespoon olive oil and black pepper until smooth. Taste and adjust seasoning with salt or more lemon if desired. Chill until ready to assemble.

Assembly & Buns

Toast the buns

Halve challah buns. Melt 2 tablespoons butter in a skillet over medium heat and toast cut sides until golden, about 1–2 minutes.

Build the sandwich

Spread a generous tablespoon of lemon caper aioli on both cut sides of the toasted bun. Place a handful of dressed hippie greens on the bottom bun, top with the hot schnitzel, then a mound of pickled onion. Add a squeeze of lemon wedge over the schnitzel if desired. Cap with the top bun and press gently.

Serve

Serve immediately while schnitzel is hot and crisp. Provide extra aioli and lemon wedges at the table.