It is shown that any convex function can be approximated by a family of differentiable with Lipschitz continuous gradient and strongly convex approximates in a "self-dual" way: the conjugate of each approximate is the approximate of the conjugate of the original function. The approximation technique extends to saddle functions, and is self-dual with respect to saddle function conjugacy and also partial conjugacy that relates saddle functions to convex functions.

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R. Goebel. “Self-Dual Smoothing of Convex and Saddle Functions.” Journal of Convex Analysis 15 (2008), No. 1, 179–190.