We study the correlated electronic structure of single-layer iridates based on structurally undistorted Ba2IrO4. Starting from the first-principles band structure, the interplay between local Coulomb interactions and spinorbit coupling is investigated by means of rotational-invariant slave-boson mean-field theory. The evolution from a three-band description towards an anisotropic one-band (J = 1/2) picture is traced. Single-site and cluster self-energies shed light on competing Slater- and Mott-dominated correlation regimes. A nodal/ antinodal Fermi-surface dichotomy is revealed at strong coupling, with an asymmetry between electron and hole doping. Electron-doped iridates show clearer tendencies of Fermi-arc formation, reminiscent of hole-doped cuprates.