1. Preheat your oven to 400°F (200°C). In a small bowl, whisk together the honey, Dijon mustard, olive oil, soy sauce, garlic powder, salt, and pepper until well combined.
2. Place the chicken breasts in a baking dish, and pour about two-thirds of the honey mustard mixture over the top, turning the chicken to coat it evenly. Reserve the remaining sauce for later.
3. In a separate bowl, toss the bell pepper, broccoli, and red onion with olive oil, salt, and pepper.
4. Spread the veggies around the chicken in the baking dish, ensuring they are evenly distributed.
5. Bake in the preheated oven for about 25-30 minutes, or until the chicken is cooked through and the veggies are tender. The chicken should reach an internal temperature of 165°F (75°C).
6. Remove the dish from the oven and let it rest for a few minutes. Drizzle the reserved honey mustard sauce over the chicken.
7. To assemble the bowls, divide the cooked rice among four bowls. Slice the chicken and place it on top of the rice. Add the roasted veggies to each bowl.

Remember, cooking is as much about intuition as it is about following steps. If your veggies need a bit more time, or if you prefer them with a little crunch, go with what feels right to you.