A 24-ounce jar of tomato puree has a little more than 3 cups, so you can always fill the jar with 1 cup water and shake to loosen the leftover tomato puree to make 4 cups.
Regarding prepared horseradish, check the ingredient list carefully! Most store-bought jars contain ingredients that don't pass the kitchen test. Bubbie's is my favorite.
Don’t be afraid to be creative with your presentation. Instead of rimming the glasses with salt, spackle the tops with a blend of freshly ground black pepper, paprika, and lemon zest for color and extra spice.