1. Soak Poppy Seed or Posto in plain water for 30 minutes.
2. Make a thick paste using Shil Nora or a food processor.
3. I prefer to add 1 green chili while making the paste.
4. Add a little salt to the Poppy Seed Paste.
5. In case you are not available with a Shil Nora (shil batta) or food processor, use the dry jar of a mixer grinder to make the paste by adding water.
6. Wash Potatoes thoroughly.
7. Remove the skin.
8. Cut into small cubes and soak in water.
9. Soaking potatoes is required else potatoes will turn dirty light brown in color.
10. Now heat 3 Tbsp. oil in a deep bottom pan.
11. Temper it with Onion Seed or Kalo jeera. 
12. Add Potato cubes.
13. Fry on a medium flame for 3-4 minutes or till Potatoes soften a bit.
14. Now add a little salt and give it a mix and add green Chilies.
15. Cook for 2 minutes.
16. Add Poppy seed paste and mix.
17. Cook till the raw smell of Poppy Seed paste gone completely.
18. Add 1 cup of water to cover the potatoes and cover the pan with a lid.
19. Cook till potatoes soften completely and adjust water if required.
20. Adjust gravy according to your preference. I prefer a medium-thick gravy.
21. Once done add 1 Tbsp. Mustard oil and mix.
22. Serve it hot with steamed rice and Biulir Dal.

Aloo Posto Recipe Video