Thakkali Chutney/Tomato-Garlic Chutney

My recipe calls for tomatoes and tamarind, but as my friend suggested, the tamarind can be replaced with vinegar. This may also reduce the quantity of oil for all those who worry about it. Try either way.
You will need:
Tomato- 2 lbs
Garlic-2 pods (14 big cloves)
Red chili powder-2 tsp
Tamarind Extract- 5tbsp (If made from fresh tamarind)
Sugar-1tsp
Canola/vegetable Oil-4tbsp
Salt-1/2 tsp(to taste)
Fenugreek Seeds-1/2 tsp
Mustard Seeds- ½ tsp
Curry leaves-one sprig

Preparation:
1. Cut the tomatoes into small cubes and measure 6 cups and keep aside. Cut the garlic into halves along its length. If using fresh tamarind, soak a small ball in warm water and extract the juice. If using the store bought tamarind, use very little as it is in concentrated form. How much tamarind to use depends on the sourness of the tomato. Dry roast the fenugreek seeds in a pan on low heat for a couple of minutes till its aroma rises and then powder the seeds and keep aside.
2. Heat all the oil in a heavy bottom pan. After a minute, lower the heat and add the mustard seeds and cover till it finishes spluttering. Now add the curry leaves. Then add the garlic, fry a bit and add tomatoes, tamarind extract and chili powder.
3. Cover and cook on low heat for about 5-10 minutes, till the tomatoes turn pulpy. Open and add sugar, salt and further cook, stirring all the while. The whole mass should come together and release all its oil.
4. Check the taste and add more sugar or spice if needed. If it looks dry,add more oil and let it fry on low heat. This oil acts as a preservative. If it is for immediate consumption, you don't need to add a lot of oil. Take it off the flame,add the fenugreek powder and let it cool. Only after it cools, store it in a bottle in refrigerator.