Heat oil in a pressure cooker and sauté chopped onions until soft.
Add potato fries and stir well.
Add achari masala along with all the dry spices (fennel, coriander, nigella, mustard, cumin, fenugreek, red chili powder, crushed chilies, whole red chilies, turmeric, and salt). Mix well and cook for 3-4 minutes.
Add blended tomatoes with green chilies. Cook for 2 minutes.
Add ½ cup water, close the lid, and pressure cook for 5 minutes.
Release steam, mix gently, and serve hot with naan or paratha.