We address the construction of four-dimensional N=2 supersymmetric nonlinear
sigma models on tangent bundles of arbitrary Hermitian symmetric spaces
starting from projective superspace. Using a systematic way of solving the
(infinite number of) auxiliary field equations along with the requirement of
supersymmetry, we are able to derive a closed form for the Lagrangian on the
tangent bundle and to dualize it to give the hyperkahler potential on the
cotangent bundle. As an application, the case of the exceptional symmetric
space E_6/SO(10) \times U(1) is explicitly worked out for the first time.Comment: 17 page