IceCube has established neutrino astronomy as a research field. My project will focus on two key aspects of high-energy astrophysical neutrinos: the characterization of the astrophysical flavor composition, and extending the reach to higher energies with the radio technique. With the Starting Grant, I will be able to hire a PhD student to improve techniques used to identify the flavor of high-energy neutrino events registered with IceCube. Here, the tau flavor is of high importance, as tau neutrinos are not produced in the atmosphere in significant amounts, and are thus predominantly of cosmic origin. I also intend to use parts of the Starting Grant to set up a hardware laboratory to develop and test components of new detectors for higher-energy neutrinos for the planned IceCube-Gen2 facility, and for research-related travel.