Prepare the ratatouille: Preheat the oven or a grill to 375 degrees F.
Make a rectangle packet bottom half the size of your baking sheet using aluminum foil. Pour in the marinara sauce. Add the veggies in a pattern of zucchini, yellow squash, zucchini, yellow squash, onion, and repeat. Once done, brush the top with olive oil and sprinkle with Italian seasoning, salt and pepper. Cover and close with aluminum foil. Place on the baking sheet and in the oven or grill and cook for 20 minutes.
For the fish: Meanwhile, in a small bowl, mix the butter, mustard, paprika, chili powder and garlic. Sprinkle the fish on all sides with salt and pepper. Make a foil packet bottom for the fish. For each piece of fish, place an equal amount of the spice butter on the foil, then place the fish on top and top with another equal amount of the spice butter. Cover with another piece of foil.
Once the ratatouille has cooked 20 minutes, remove the baking sheet and remove the top from the foil packet. Place the fish packet on the baking sheet next to the ratatouille and return to the oven. Bake for about 15 minutes.
For the rice: Squeeze the rice in the bags to loosen. Make a packet bottom a quarter of the size of the baking sheet and add the rice, cilantro and lime zest. Gently stir with a fork, then top and close tightly with another piece of foil. Place on the final space on the baking sheet next to the fish packet. Bake until the rice is hot, another 5 minutes.
Remove the cheat sheet from the oven. Carefully open the fish packet and allow the steam to escape. Carefully open the rice packet, then spritz with lime juice and fluff. Serve immediately.