Rare semileptonic $b \to s \ell^+ \ell^-$ transitions provide some of the most promising framework to search for New Physics effects.
Recent analyses of these decays have indicated an anomalous pattern in measurements of angular distributions of the decay
$B^0 \to K^{*0} \mu^+\mu^-$ and in lepton-flavour-universality observables.
We propose a novel approach to independently and complementary clarify the nature of these effects
by performing a simultaneous amplitude analysis of $B^0 \to K^{*0} \mu^+\mu^-$ and $B^0 \to K^{*0} e^+ e^-$decays.
This method allows the direct determination of the difference of the Wilson Coefficients $C_9$ and $C_{10}$ between electrons and muons,
which are found to be insensitive to both local and non-local hadronic contributions.
We show that considering the current preferred New Physics scenario a first observation of LFU breaking in a single measurement is possible with LHCb Run-II dataset.
The potential for a claim of New Physics analysing $B^0 \to K^{*0} \mu^+\mu^-$ decays alone is also examined
and prospects for disentangling New Physics effects from non-local hadronic contributions are investigated.