Wash and dry all produce. Preheat oven to 400 degrees. Halve red and yellow bell peppers lengthwise. Remove core, seeds, and white ribs. Rub with a drizzle of olive oil. Season with salt and pepper. Place on a baking sheet cut-side down. Roast in oven until soft, about 20 minutes.

Meanwhile, bring 11/2 cups water and stock concentrate to boil in a small pot. Once boiling, add golden grain blend. Lower heat and reduce to a simmer. Cover and cook until tender, 10-12 minutes. Remove from heat and keep covered.

Halve, Peel, and dice shallot. Mince or grate garlic. Finely chop sun-dried tomatoes. Chop zucchini into 1/2-inch pieces. Cut mozzarella into small cubes. Finely chop parsley.

Heat a drizzle of oil in a large pan over medium-high heat. Add shallot and sun-dried tomatoes. Cook, tossing, until shallots are softened, 3-4 minutes. Add garlic and cook until fragrant, about 1 minute. Season with salt and pepper. Transfer mixture to a large bowl.

Increase heat to high and heat another drizzle of oil in same pan. Add zucchini. Season with salt, pepper, and herbs de Provence. Cook, tossing, until soft and lightly charred, 5-7 minutes. Add to bowl with sun-dried tomato mixture. Toss to combine. Fluff golden grain blend with a fork, then add to bowl along with mozzarella and toss. Season with salt and pepper.

Flip bell peppers over and fill with as much stuffing as will fit. Return sheet to oven and bake until mozzarella melts, 3-5 minutes. Stir parsley into remaining stuffing, then divide mixture between plates. Top with stuffed pepper halves.