Preheat the air fryer to 400°F (200°C) and the oven to 400°F (200°C).

Prepare Air Fryer French Fries: Scrub the russet potatoes and cut them into thin, uniform strips. Place them in a bowl of water to soak for a few minutes, then drain well. In a bowl, toss the potatoes with extra-virgin olive oil, garlic powder, paprika, salt, and black pepper, ensuring they are evenly coated.

Cook the French Fries: Place the seasoned potatoes in the air fryer basket and cook at 400°F (200°C) for about 20 minutes, shaking or flipping them halfway through, until crispy and golden.

Prepare the Bratwurst: Place the bratwurst on a baking sheet and cook in the oven at 400°F (200°C) until it reaches an internal temperature of 155°F (68°C), using a thermometer to ensure it's fully cooked.

Make the Curry Ketchup Sauce: While the bratwurst is cooking, heat the vegetable oil over medium heat in a saucepan. Add the chopped onion and sauté until translucent, about 3 minutes. Stir in the minced garlic and cook for another minute until fragrant. Add the curry powder, paprika, cayenne pepper, salt, and black pepper, cooking for 2 more minutes to toast the spices. Pour in the ketchup and water, stirring to combine. Let the sauce simmer over low heat for 5 - 7 minutes, stirring occasionally.

Slice the Bratwurst: Once the bratwurst is cooked to an internal temperature of 155°F (68°C), slice it into bite-sized pieces.

Prepare the Lemonade: Mix the fresh squeezed lemon juice, water, and sugar in a pitcher. Stir until the sugar dissolves and serve over ice.

Serve: Pour the curry ketchup sauce over the sliced bratwurst, tossing to coat well. Serve the currywurst with a side of French fries and homemade lemonade.