Just use some diced fresh jalapeno pepper
Or choose another recipe... there are a million of good ones that don't call for jalapeno juice
You are right though, there are tons of other recipes out there..but that's not exactly the point of this forum
Puree 2 or 3 jalapeno peppers in a blender or food processor. Then, pour this mixture through a strainer to strain out any pulp and make the juice smoother.