My mom fries onions and stores them in fridge. Also, for tarka in daals, she fries onions, zeera, lal mirch and stores that too.. but I think it's only for 3-4 days, not more. It's real fast.
my mom does that also, she makes her own ginger and garlic paste, stores some in freezer, some in fridge. She also makes her own tomatoe puree and freezes it also. These are some good ways to save time. And it's not store-bought!