<p>Wave vortices, structures carrying helical phase fronts and orbital angular momentum (OAM), drive transformative advances in fields from super-resolution imaging to high-capacity communications. Yet in elastic wave physics, a fundamental constraint has persisted: the quasi-two-dimensional confinement of Lamb waves suppresses the out-of-plane phase helicity required for conventional vortex formation. Here, this restriction is lifted through the realization of a spatiotemporal elastic-wave vortex (STEV) carrying transverse OAM, enabled by a mirror-symmetry-broken metagrating operating on <i>A</i>₀-mode Lamb waves. The structure simultaneously performs spatial and temporal differentiation on the incident pulse, encoding a spiral phase in momentum-frequency space that maps to a propagating wave packet with a vanishing central amplitude and 2π phase winding. This passive platform couples dark modes to radiation and engineers a transfer function that acts as an intrinsic spatiotemporal differentiator. Laser vibrometry confirms the phase singularity and its dynamic evolution, while edge-detection demonstrations on amplitude-modulated pulses illustrate the structure’s potential for real-time ultrasonic image processing. By circumventing the geometric constraints that have long confined elastic vortex phenomena, our work establishes a compact architecture for spatiotemporal pulse shaping in solids, opening routes to contactless particle manipulation, on-chip nondestructive evaluation, and wave-based analog computing in the elastic domain.</p>