Commercial yuzu kosho is typically a paste, but homemade versions can be a little chunkier. You can control the texture by grinding or pureeing to your taste. Traditionally, green, unripe yuzu are matched with green chilis, whereas yellow, ripe yuzu go with red chilis for two different kinds of yuzu kosho. Where I live, red chilis are hard to come by this time of year, so I made mine with ripe yuzu and green jalapenos.
Place the chili pepper in a mortar and pestle. Add salt, and grind to the desired texture. Add yuzu zest and grind to combine. (Alternatively, place all ingredients in a blender or food processor and puree to a fine paste.) Put in a clean jar, pack down, and allow to rest at room temperature for at least an hour; overnight is better.