Investigating a puri

Back to the first question: why is one side of a puri thinner than the other? And why does it puff up like a balloon in hot oil, the way a bhatura does, or a phulka on the flame?

You don't need a fancy laboratory with flasks and pipettes. Your kitchen is a lab. So is the playground, or the classroom window, wherever you stop and ask why? or what happens if...?

Start with a scientific question: what are the things that may change the way a puri puffs up? Then sort out two lists.

Now the one rule that makes it all work: change only one thing at a time, and keep everything else the same. Suppose you use new dough and smoking-hot oil and a new way of dropping it, all at once. If the puri puffs better, you will never know which change did it.

So to test the oil, fry it boiling hot, hot, and not very hot, but use circles of dough of the same thickness and drop them in the same way.

Write everything down, including what you see, hear and smell. Did the oil splatter, smell or smoke? One round of tests will give you new questions: do puris puff better from fresh dough or stored dough? What if you prick a hole in it before frying?

This is how every experiment is done, from the simplest to the most complicated. The book calls it systematic investigation. And here is a surprise: even a puri puffing is not completely understood by scientists today.