  Quasi-periodic eruptions (QPEs) are repeating thermal X-ray bursts associated
with accreting massive black holes, the precise underlying physical mechanisms
of which are still unclear. We present a new candidate QPE source, AT 2019vcb
(nicknamed Tormund by the ZTF collaboration), which was found during an
archival search for QPEs in the XMM-Newton archive. It was first discovered in
2019 as an optical tidal disruption event (TDE) at $z=0.088$, and its X-ray
follow-up exhibited QPE-like properties. Our goals are to verify its robustness
as QPE candidate and to investigate its properties to improve our understanding
of QPEs. We performed a detailed study of the X-ray spectral behaviour of this
source over the course of the XMM-Newton archival observation. We also report
on recent Swift and NICER follow-up observations to constrain the source's
current activity and overall lifetime, as well as an optical spectral
follow-up. The first two Swift detections and the first half of the 30 ks
XMM-Newton exposure of Tormund displayed a decaying thermal emission typical of
an X-ray TDE. However, the second half of the exposure showed a dramatic rise
in temperature (from 53 to 114 eV) and 0.2-2 keV luminosity (from
$3.2\times10^{42}$ to $1.2\times10^{44}$ erg s$^{-1}$). The late-time NICER
follow-up indicates that the source is still X-ray bright more than three years
after the initial optical TDE. Although only a rise phase was observed,
Tormund's strong similarities with a known QPE source (eRO-QPE1) and the
impossibility to simultaneously account for all observational features with
alternative interpretations allow us to classify Tormund as a candidate QPE. If
confirmed as a QPE, it would further strengthen the observational link between
TDEs and QPEs. It is also the first QPE candidate for which an associated
optical TDE was directly observed, constraining the formation time of QPEs.
