We show that the kinetics of recombination of holes bound at accepters from a delta-doped monolayer in a heterostructure with magnetically frozen two-dimensional (2D) electrons evolves according to the power law I(t) proportional to t(-1). This behavior is universal for any kind of 2D electron insulator (ordered or disordered) in the ultra-quantum-limit and follows over a wide time range after the photoexcitation pulse. The difference between ordered and random insulating phases shows up at the longest time delays: The ordering of electrons into a Wigner lattice yields an asymptotical single lifetime decay tail, with a recombination rate whose temperature dependence is described by the characteristic Debye-Waller-type factor.