Heat a large nonstick pan over medium heat. Once the pan is hot, add the oil and chicken, brown on all sides, then remove from the pan and set aside. Add in the peppers and onion, saute until they start to soften, then add the garlic, tomatoes, paprika, and thyme and cook until the garlic starts to turn golden brown.
Add the wine and stir until it mostly evaporates. Then add the broth, rice, and saffron (if using). Season with salt and pepper. Add the chicken back to the pan and cover with a lid. Reduce the heat to a low simmer and cook until the rice is tender and the chicken reaches an internal temperature of 160 degrees using a thermometer.
Once the rice is tender stir in the peas and lemon zest. Remove from the heat, season to taste with salt and pepper.