Whisk olive oil, soy sauce, lemon juice, honey, garlic, smoked paprika, cumin, salt and pepper in a bowl. Add chicken, toss to coat, cover, and refrigerate 20 minutes to 2 hours.
Thread chicken onto skewers, leaving small gaps between pieces. Add veggies if using. Pat chicken dry before threading for better char.
Preheat grill or grill pan to medium-high and oil grates. Grill skewers 3–4 minutes per side, rotating for even char, until chicken reaches 165°F (74°C).
Let skewers rest 3–5 minutes. Finish with lemon and chopped herbs. Serve with tzatziki, rice, or pita.
Notes
Do not marinate longer than 4 hours if using a lot of citrus to prevent texture changes.
Use thighs for a more forgiving, juicy result; breasts will also work if monitored closely.
Store cooked skewers in an airtight container for up to 3 days.