In a large bowl, combine grated onion, ground beef, breadcrumbs, salt, black pepper, heavy cream, and egg. Mix gently with your hands until just combined.

Divide the mixture into four equal portions and roll them into balls. Gently flatten each ball into a patty about ¾ inch thick.

In a large skillet, heat a mixture of olive oil and unsalted butter over medium heat. Add the patties, cooking for 4-5 minutes on each side until browned.

In the same skillet, add the diced onion and minced garlic, stirring for about 2 minutes. Add salt, pepper, and flour to create a roux.

Slowly pour in the chicken broth, bringing it to a simmer. Add the heavy cream and stir in the chopped dill. Cook until creamy.

Return the seared patties to the skillet, simmering in the creamy dill sauce for an additional 5-6 minutes.