Smell business

This morning while making poha, out of onions, the seasoning was a short affair and finally chilli powder joined the heated oil. The smell then reminded me of other dishes(tamarind rice as it uses red whole chillies in seasoning) and to reach that final product, I added lemon juice, dont ask me why. I am wondering can we imagine a smell we want and actually figure whats the missing ingredient.
Recently while making canele, I realised that milk boiled with sugar smells like custard.