2. Drizzle the halibut fillets on both sides with 1 tablespoon of olive oil and season with salt and pepper. Place the fillets on a baking sheet and sprinkle with chives and tarragon.
3. Place the baking sheet in the oven and roast until the fish is just opaque in the center, about 10 to 14 minutes, depending on the thickness of the fillets.
4. Meanwhile, heat the remaining tablespoon of olive oil in a medium-size skillet over high heat. Add the summer squash and zucchini and sauté for 1 minute. Add the mushrooms and cook for 4 more minutes. Add the garlic, tomatoes, and corn and cook for 1 to 2 minutes more.
5. Place a bed of vegetables on each plate. Place a piece of fish on top of the vegetables and drizzle each fillet with fresh lemon juice.