Onion rings "Cheeseburger"

Ingredients:

• 1/4 cup ketchup
• 1/4 cup mayonnaise
• 2 tbsp mustard
• 1 pickled cucumber, chopped
• 2 large onions
• 220 g of ground beef
• 1/3 cup grated sharp cheddar
• 1 cup of milk
• 1/4 cup vegetable oil + extra for frying
• 1 teaspoon baking powder
• 1 tsp onion powder
• 1 large egg
• 1.5 cups of flour
• 1 tbsp sesame seeds
• Special equipment: deep fat thermometer

Preparation:

1. In a small bowl, combine ketchup, mayonnaise, mustard and pickle (this is a special sauce).
2. Cut a 2-cm-thick slice from the end of each onion. Peel and slice the onions into 1-cm-thick rounds. Separate the rings and set aside the 8 largest rings. Set aside 8 more rings, each 2.5 cm smaller in diameter. Set aside the remaining onions for another use.
3. In a medium bowl, combine ground beef, cheese, 1/4 cup special sauce, 1 1/2 teaspoons salt, and 1/4 teaspoon black pepper until evenly distributed.
4. Place large onion rings on a parchment-lined baking sheet. Spread 1 teaspoon of the meat mixture evenly around the inside of each ring, leaving a hole in the middle. Insert a smaller ring into the center of each large ring of meat mixture, shaping them like donuts.
5. Place in the freezer for about 1 hour until the meat is completely set.
6. In a small bowl, whisk together the milk, vegetable oil, baking powder, onion powder, egg, 1 cup flour, and 1/2 teaspoon salt until smooth. Place the remaining 1/2 cup flour in another small bowl.
7. Fill a large saucepan with vegetable oil to a depth of 7 cm and attach a deep-fry thermometer to the side. Heat the oil to 190°C (350°F). Dredge the rings, one at a time, in flour, shaking off any excess. Then dip them in the batter, letting any excess drip back into the bowl. Sprinkle with sesame seeds and carefully lower them into the hot oil.
8. Fry, turning once, until the rings are golden brown and puffy, 2-3 minutes per side. Before the next batch, heat the oil again to 190°C.
9. Transfer the onion rings to a paper towel-lined baking sheet. Serve with the remaining onion dipping sauce for dipping and eating.