  Characterizing the 125 GeV Higgs is a critical component of the physics
program at the LHC Run II. In this Letter, we consider $t\bar{t}H$ associated
production in the dileptonic mode. We demonstrate that the difference in
azimuthal angle between the leptons from top decays can directly reveal the
CP-structure of the top-Higgs coupling with the sensitivity of the measurement
substantiality enhanced in the boosted Higgs regime. We first show how to
access this channel via $H \to b\bar{b}$ jet-substructure tagging, then
demonstrate the ability of the new variable to measure CP. Our analysis
includes all signal and background samples simulated via the MC@NLO algorithm
including hadronization and underlying-event effects. Using boosted Higgs
substructure with dileptonic tops, we find that the top-Higgs coupling strength
and the CP structure can be directly probed with achievable luminosity at the
13 TeV LHC.
