  We develop an algebraic structure modeling local operators in a
three-dimensional quantum field theory which is partially holomorphic and
partially topological. The geometric space organizing our algebraic structure
is called the raviolo (or bubble) and replaces the punctured disk underlying
vertex algebras; we refer to this structure as a raviolo vertex algebra. The
raviolo has appeared in many contexts related to three-dimensional
supersymmetric gauge theory, especially in work on the affine Grassmannian. We
prove a number of structure theorems for raviolo vertex algebras and provide
simple examples that share many similarities with their vertex algebra
counterparts.
