We present a feasible scheme for performing an optically controlled phase gate between two conduction lectron spin qubits in adjacent self-assembled quantum dots. Interaction between the dots is mediated by the unneling of the valence hole state, which is activated only by applying a laser pulse of the right polarization nd frequency. Combining the hole tunneling with the Pauli blocking effect, we obtain conditional dynamics or the two quantum dots, which is the essence of our gating operations. Our results are of explicit relevance to the recent generation of vertically stacked self- assembled InAs quantum dots, and show that by a design which voids unintended dynamics the gate could be implemented in theory in the 10-ps range and with a fidelity over 0%. Our proposal therefore offers an accessible path to the demonstration of ultrafast quantum logic in quantum dots.