1. Bring a large pot of salted water to a boil. Add turnips and potatoes and boil until fork-tender, 4 to 6 minutes. Drain and transfer to a baking sheet to cool completely.
2. Heat 1/2 cup oil in a large skillet over medium-high heat until shimmering. Add celery, onions, and garlic, and cook, stirring frequently, until onions are golden brown, 10 to 12 minutes. Transfer to a large bowl.
3. Wipe the skillet and heat remaining 1 cup oil over medium-high heat until shimmering. Working in 3 batches, cook turnip-potato mixture until golden brown and crispy, 5 to 7 minutes. Transfer to bowl with celery-onion mixture and repeat with remaining batches.
4. Add aioli to bowl and toss to combine. Season with salt and pepper to taste and transfer to platter. Top with trout, celery leaves, and parsley, and drizzle with extra aioli.
Source: Hannaford fresh Magazine, November - December 2015