Question

we add salt to vegetables during cooking as the vegetables release energy what mechanism is involved in it

Answer 1

The vegetables cells have higher concentration of water when compared to the solution it is kept in, which is hypertonic i.e. lower in water concentration, as salt is added to it.
So, as we know water molecules move from higher to lower concentration. The water from the cells of the vegetables moves out through semi-permeable plasma membrane i.e. osmosis.