If the chicken breasts are thick, slice them horizontally into thinner cutlets or lightly pound the thickest parts so they cook evenly. Mix the olive oil, lemon juice, garlic, salt, black pepper, paprika, and oregano if using. Coat the chicken well and let it sit for 15–20 minutes. Keep the marinade short. Lemon helps brighten the chicken, but too much time in acid can tighten the outside of chicken breast. That specifically brief window is calibrated to season and lightly brighten the meat without giving the acid enough time to work its way into the surface protein and compromise the finished texture.

Heat a grill pan, cast iron pan, or outdoor grill over medium-high heat. Cook the chicken for 3–5 minutes per side, depending on thickness, until lightly charred and cooked through. The internal temperature should reach 74°C. Transfer to a board and rest for 5–10 minutes, then cut into bite-size pieces. Rest the chicken before slicing. If you cut it immediately, the juices run out and the salad gets watery. During cooking, the chicken's own juices are pushed toward the centre under real pressure, and that rest period lets them redistribute evenly back through the meat rather than spilling out directly into the salad if cut too soon.

Dice the tomatoes, cucumber, and roasted red peppers. Slice or finely dice the red onion. Chop the parsley. Place the tomatoes, cucumber, roasted peppers, red onion, and most of the parsley in a large bowl. Keep the vegetable cuts medium-small but not minced. Shopska should feel juicy and rustic, not like salsa. That specific cut size protects the salad's own intended character — pieces cut too finely would break down and release moisture too readily, pushing the texture toward something closer to a fine salsa than the rustic, chunkier salad this dish is meant to be.

In a small bowl, whisk together the olive oil, vinegar, lemon juice, salt, and black pepper. Taste carefully. The dressing should be simple, sharp, and lightly salty because the cheese will add more salt on top. That deliberate restraint on salt in the dressing itself accounts for the substantial salt already coming from the generous layer of cheese still to come — seasoning the dressing as if the cheese weren't there would risk oversalting the finished dish.

Pour the dressing over the vegetables and toss gently. Let the salad sit for 5 minutes so the tomatoes release a little juice and the dressing becomes more integrated. Do not overdress it. Shopska should be juicy from the tomatoes and cucumber, not swimming in oil. That brief, deliberately short rest lets the tomatoes contribute just enough of their own natural juice to the dressing without extending long enough for the vegetables to release considerably more moisture than intended.

Transfer the dressed salad to a wide serving bowl. Scatter the grilled chicken pieces over the vegetables. Cover generously with finely grated sirene or firm white brined cheese. Finish with the remaining parsley and a little black pepper. Grating the cheese finely, rather than crumbling it, is what produces that classic, heavy white blanket effect covering the entire surface of the salad, distinct from the more scattered look coarser crumbles would give.

Serve immediately while the vegetables are fresh and crisp and the chicken is still slightly warm. This salad's whole appeal depends on that fresh, juicy vegetable base against warm chicken — any real delay lets the tomatoes and cucumber release considerably more water, diluting the dish before it's even served.