Pot-au-Feu Arancini with Horseradish Aioli

**Prepare the Arancini Filling:** In a large bowl, combine the cooked arborio rice, shredded beef, diced vegetables, Parmesan cheese, and 1 beaten egg. Season with salt and pepper to taste. Mix well to combine.

**Form the Arancini:** Using your hands, take about 2 tablespoons of the rice mixture and form it into a ball. Ensure the mixture is packed tightly. Repeat with the remaining rice mixture.

**Bread the Arancini:** Set up a breading station with three shallow dishes. In the first dish, place the flour. In the second, place the beaten eggs. In the third, place the breadcrumbs.

Roll each arancini in the flour, then dip it in the beaten egg, and finally coat it evenly with breadcrumbs. Place the breaded arancini on a baking sheet lined with parchment paper.

**Fry the Arancini:** Heat the vegetable oil in a deep fryer or a large, heavy-bottomed pot to 350°F (175°C).

Carefully place a few arancini at a time into the hot oil. Fry for 3-4 minutes, or until golden brown and crispy on all sides. Remove the arancini with a slotted spoon and place them on a wire rack to drain excess oil.

**Prepare the Horseradish Aioli:** While the arancini are frying, whisk together the mayonnaise, horseradish, and lemon juice in a small bowl. Season with salt and pepper to taste. Adjust the amount of horseradish to your preferred level of spiciness.

**Serve:** Serve the warm arancini immediately with the horseradish aioli for dipping.