Heat oven to 350F.
Bring a medium pot of water to a boil. Add the green beans and blanch 1 minute. Transfer green beans immediately to an ice bath to stop the cooking. Drain.
Heat 1 T olive oil in a large nonstick saucepan on high heat. Once hot, add the onion and saute 1 minute to brown. Add the zucchini and yellow squash, and saute, tossing occasionally, 2 minutes to lightly brown (you just want them lightly browned; they will finish cooking in the oven with the stuffing). Transfer veggies to a large mixing bowl. Add salt, pepper, stuffing, and blanched green beans.
In a small bowl, combine the egg and vegetable stock. Pour over the vegetables and stuffing and toss to combine all the ingredients. Transfer to a 13x9 baking dish sprayed with cooking spray. Cover dish tightly with foil. Bake at 350F for 40-45 minutes until heated through and the veggies are cooked but not too soft.
While the stuffing is cooking, prepare the fish. Line a bake sheet with foil for easy clean-up. Lay the fish on the foil. Season well with salt, pepper, and Old Bay. Bake at 350F for 15 minutes or just until fish flakes easily with a fork.
To make the Lemon-Dill Sauce, heat the butter in a small saucepan over medium heat. Add the flour and whisk until smooth and bubbly. Cook 2 minutes to cook the flour. Slowly whisk in the milk and cook, stirring constantly, 5 minutes or until slightly thickened. Remove from the heat and add salt, dill, lemon juice, and zest. Taste for seasoning.
To serve, put a couple large spoonfuls of stuffing on the plate. Lay a piece of salmon over (I remove the salmon skin at this point - I keep it on for cooking because it keeps the fish from drying out). Spoon sauce over and garnish with a pinch of fresh dill. Yield: 6 servings.