I think the bare minimum you need is a condenser microphone (USB/Phantom power) and a pop filter. You would also need a stand for mounting the mic as well as your pop filter. Theoretically, you could use the OTG cable and connect the mic to your mobile, but I think having a laptop would be a better option. Also, invest in a sound card if you can.
Look for Behringer C-1, or the low end models from Samson. I personally use Samson Go Mic, and I am quite happy with it (I use it for recording musical instruments such as Guitar).