Pressure cook the potatoes and cut them into cubes.
In a mortar and pestle add the pepper, cumin seeds, and fennel seeds.
Crush this into a powder.
Alternatively you can pulse this in a mixie too.
In a pan add oil, mustard seeds, and curry leaves.
Once the mustard splutters add the finely chopped onion.
Add turmeric powder, salt, and red chili powder.
Now add the freshly ground pepper masala powder.
I first added 1 tbsp of it then added the remaining too.
Let this cook on medium-low flame for 10-12 minutes.
Keep stirring in between.
Once the bottom portion gets roasted, switch off the flame.
Serve potato pepper fry with hot rasam rice or sambar sadam.
It goes well with curd rice too.