Preheat the oven to 350°F. Spray 4 baking sheets with cooking spray.

Finely grate the onions or puree them in a food processor. Combine the onions with the beef, prune butter, tomato paste, lemon juice, and salt in a large bowl. Mix until very well combined and completely smooth.

Place the pizza rounds on the prepared baking sheets and top each round with about 1 tablespoon of the meat sauce. With the back of a spoon, spread the sauce all the way to the edges.

Bake until the meat mixture is cooked through, about 30 minutes. Serve warm.

From the Joy of Kosher Cookbook, order your copy for 199 more recipes.