Prep the chicken and veggies. Pat the chicken dry and season with 1 teaspoon salt, 1/2 teaspoon pepper, and the Italian seasoning.
Set the asparagus, peas, carrots, onion, zucchini, garlic, and lemon aside so they’re ready to go.
Sear the chicken. Heat 1 tablespoon olive oil in a large skillet over medium-high heat. Add chicken in a single layer and cook 5–7 minutes, turning once, until golden and cooked through. Transfer to a plate and tent loosely with foil.
Sweat the aromatics. Reduce heat to medium.
Add remaining 1 tablespoon olive oil and the butter. Add onion and carrots with a pinch of salt. Cook 4–5 minutes, stirring, until the onion softens and the carrots start to tenderize.
Add quick-cooking veggies. Stir in asparagus and zucchini.
Cook 3–4 minutes until bright green and crisp-tender. Add garlic and cook 30 seconds, just until fragrant.
Deglaze and build the sauce. Pour in chicken broth. Scrape up browned bits from the pan.
Whisk in Dijon, lemon zest, and lemon juice. If you like a touch of sweetness, add honey. Simmer 1–2 minutes to marry the flavors.
Finish with peas and chicken. Stir in peas and return the chicken (and any juices) to the skillet.
Toss to coat. Warm through 1–2 minutes. Taste and adjust salt, pepper, and lemon.
Garnish and serve. Sprinkle with parsley and a pinch of red pepper flakes if you like heat.
Serve as is, or over gluten-free rice, quinoa, or mashed potatoes.