Preheat oven to 425°.
Toss the potatoes in olive oil and par roast for about 30 minutes, turning halfway.
While potatoes are cooking, wrap each triggerfish fillet in a slice of prosciutto and drizzle olive oil over each fillet. Heat some oil in a pan and sear fillets for 5 minutes on each side. Set aside.
When potatoes are done, toss together with asparagus, zucchini, cherry tomatoes, garlic, basil and oregano in olive oil to coat. Season lightly with salt and pepper. Place in a baking dish and layer fish fillets on top. Reduce oven to 400° and roast for 20 minutes, until fish is flaky. To serve, squeeze lemon over the top.