The study of high energy, transient astrophysical phenomena (solar flares, pulsars, X-ray bursters, gamma ray bursts) require new instrumentation capable of simultaneously performing high spatial, temporal and spectral observations. Currently, there are no elements such as lenses or mirrors capable of reflecting or refracting X- and gamma rays. Shadow-casting techniques must be employed to image such sources. These techniques rely on the total absorption of X- and gamma rays to indirectly give images of the sources. We propose a design for a shadow-caster based on dual Fresnel Zone Plate (FZP) coders suitable for solar observations from a satellite or balloon-based platform. Most shadow-casters require an image plane detector with a spatial resolution comparable to the smallest features ct into the coder for the best angular resolution. The image plane detector for a telescope based on dual FZPs does not have such a requirement since the coders measure almost the exact Fourier transform of the source distribution. We present here the results of simulations that demonstrate the telescope's capability to produce images with an angular resolution of a few arcseconds, a temporal resolution dependent only on the source intensity, and high spectral resolution obtained using an array of solid state X-ray detectors.