  We establish that Majorana fermions on the boundary of topological
superconductors have only spin-triplet superconducting correlations independent
of whether the bulk superconducting gap is spin singlet or triplet. This is
universal for time-reversal broken (respected) topological superconductors
(TSCs) with an odd number of (pairs of) Majorana fermions on the boundary.
Consequently, resonant Andreev reflection induced by Majorana fermions only
occurs in spin-triplet channels and always injects spin-triplet Cooper pairs
into the leads. This spin-triplet condensate results in a spin-orbit coupling
(SOC) controlled oscillatory critical current without a $0$-$\pi$ transition in
the TSC/SOC-semiconductor/TSC Josephson junction. The observation of this
unique current-phase relation can serve as the definitive signal for Majorana
fermions. Our study shows a technique for manipulating Majorana fermions based
on their spin-triplet superconducting correlations.
