To a large skillet, add 2 to 3 tablespoons olive oil, chicken, season with salt and pepper, and cook over medium-high heat for about 7 minutes, or until chicken has cooked through; flip intermittently to ensure even cooking.
After chicken has cooked, transfer to a large serving platter and set aside.
Add the potatoes to the skillet, about 2 to 3 tablespoons olive oil, season with salt and pepper, stir to combine, and cook covered over medium-high heat for about 10 minutes, or until potatoes are fork tender.
After potatoes have cooked, transfer to the serving platter and set aside.
Add the haricots vert to the skillet, about 1 to 2 tablespoons olive oil, season with salt and pepper, stir to combine, and cook covered over medium-high heat for about 5 to 7 minutes, or until crisp-tender.
After haricots vert have cooked, transfer to the serving platter and set aside. While the haricots vert are cooking, make the sauce.
For the Sauce:
Add all ingredients to a small bowl, whisk to combine, taste and check for flavor balance, and make any necessary adjustments if desired, i.e. more mustard, honey, salt, etc.
Return chicken to the pan, pour the sauce over the chicken, stir, cook uncovered over medium heat for 1 to 2 minutes, or until sauce thickens slightly and chicken re-warms.
Transfer chicken to the serving platter and serve the dish immediately.
Notes
Recipe is best warm and fresh but will keep airtight in the fridge for up to 5 days.