Method involved in Dhokla preparation is

Fermentation is a biochemical process in which microorganisms such as yeast and lactic-acid bacteria act on sugars and starches in a batter, releasing carbon dioxide gas and mild acids; this gas expands and leavens the batter, giving it a light, aerated texture before it is cooked.

Dhokla is made from a batter of rice and split gram (chana dal or besan) that is soaked, ground, and left to rest for several hours so that naturally occurring microorganisms ferment it; the carbon dioxide produced during this fermentation gets trapped in the batter, and the batter is then steamed, which sets this trapped gas into the dish's signature soft, spongy structure.

• Shallow frying cooks food in a thin layer of hot oil in a pan, as with parathas or dosas, using direct oil-to-surface heat rather than any gas-producing microbial action in the batter.

• Deep-frying immerses food completely in hot oil, as with samosas or pooris, cooking it through conducted heat rather than through fermentation.

• Boiling cooks food by submerging it in water at its boiling point, as with rice or dal, which again supplies only heat and does not leaven a batter.

None of frying or boiling introduces the gas-trapping action that produces dhokla's characteristic sponginess; only the fermentation step does.