Heat oil in a pan, add dry red chillies and toast till golden. Remove and set aside.
Add onions and saute for a min.
Add tomatoes and mix well.
Add salt and turmeric and tamarind and cook till mushy..
Take it in a blender and puree till smooth. Add water as needed. Take it in a bowl.
Heat oil in a pan, add mustard and asafoetida and mix well.
Pour it into the chutney and mix well.