Hi spadge
Not quite sure what you mean about adding a bagar because I take it you mean tempered spices cooked in hot oil and your recipe doesn't contain any reference to spices. In any case I usually start by base with the oil, heat it on medium heat then add the vegetables, garlic, ginger, salt and spices and I allow them to cook gently n the oil for 15-30 minutes. Then I add boiling water and let it all simmer for whatever time it needs, be that another hour, two or three. I am not fastidious about the latter. After that the base is sort of made, minus the tomatoes. I use tinned and put them in for the last 15-30 minutes..
Some people feel you don;t need the frying stage with oil and advocate putting the oil, water etc. in at the same time and who am I to argue otherwise. People will also suggest leaving the tomatoes till last or they will become bitter and that's what I do.
Abdul Mohed is an Indian Restaurant chef who posted here for a while and in his booklet which I bought he has an optional supplementary recipe which he calls a gravy (base) enhancement. This consists of taking a separate pan/pot, then frying garlic/ginger paste in hot oil, adding spice mix, then some tinned chopped tomatoes, and finally adding some water, boiling it all for 15 minutes and adding to the previously cooked base at the end.
Perhaps this is what you were looking for?
tomatoes