We study the ground-state phase diagram of the strongly interacting Harper-Hofstadter-Mott model at quarter flux on a quasi-one-dimensional lattice consisting of a single magnetic flux quantum in ydirection. In addition to superfluid phases with various density patterns, the ground-state phase diagram features quasi-one-dimensional analogs of fractional quantum Hall phases at fillings ν=1/2 and 3/2, where the latter is only found thanks to the hopping anisotropy and the quasi-onedimensional geometry. At integer fillings-where in the full two-dimensional system the ground-state is expected to be gapless-we observe gapped non-degenerate ground-states: at ν=1 it shows an odd 'fermionic' Hall conductance, while the Hall response at ν=2 consists of the transverse transport of a single particle-hole pair, resulting in a net zero Hall conductance. The results are obtained by exact diagonalization and in the reciprocal mean-field approximation. system in question. Furthermore, the restriction of the y-direction to just a few sites (in our case four) enables us to benchmark our RCMF results against ED, where it suffices to scale the system-size in the x-direction only.In this work we analyze the properties of the HHMm on a quasi-one-dimensional lattice, consisting of just a single flux quantum along the y-direction, while the x-direction is treated in the thermodynamical limit. For the flux of Φ=π/2 considered here, this consists of 4 plaquettes in y-direction with periodic boundaries. Such a thin-torus limit has been previously investigated in fermionic systems in the lowest Landau level, where onedimensional analogs of quantum Hall states were observed, which are predicted to continuously develop into their two-dimensional counterparts for increasing y-direction [23][24][25]. For interacting bosons an effective ladder model realizing the thin-torus limit with 2 sites in y-direction has been proposed, predicting a charge density wave analog of the two-dimensional ν=1/2 fQH phase [26].The quasi-one-dimensional limit in combination with anisotropic hopping amplitudes leads to larger many-body gaps due to the finite size in y-direction, and therefore to more stable topological phases than in in the fully two-dimensional limit. This can be a useful insight in the experimental search for bosonic topologically non-trivial phases, where robustness against the expected strong heating processes is of great importance [27]. Equally important, fillings which are expected to be always gapless in the fully two-dimensional limit [28,29] can become gapped as a consequence of the finite size, leading to unexpected new ground-states. Another feature of the quasi-one-dimensional geometry lies in its low number of sites in y-direction, which makes it possible to map the spatial y-direction onto a finite number of internal degrees of freedom (in this case 4), rewriting the system as a one-dimensional multi-component system, which in the future could be simulated by cold atoms in the synthetic dimensions concept [30][31][32][33], o...