Sauté the Vegetables: In a spacious pot, combine the butter and olive oil, warming them over medium heat. Add the sliced leek and carrots, and sauté until they soften, about 5 minutes. Stir in the garlic, salt, black pepper, and Herbes de Provence, cooking for another minute until fragrant.
Add the Broth and Cook the Veggies: Pour in the warm chicken stock, and bring the soup to a gentle simmer. Add the peas and diced baby zucchini. Let everything simmer for about 10 minutes, or until the vegetables are tender but still vibrant.
Add the Chicken and Lemon: Stir in the cooked chicken, lemon zest, and lemon juice, and cook for another 5 minutes until everything is heated through. Sample the dish and modify the seasoning by adding additional salt, pepper, or lemon juice as desired.
Add Quinoa and Fresh Herbs: Stir in the cooked quinoa and chopped basil just before serving, ensuring they’re fully incorporated and warmed through.
Serve and Garnish: Ladle the soup into bowls, garnish with fresh lemon wedges for an extra burst of citrus, and enjoy the bright, refreshing flavors!