In order to improve immunity we have to take a balanced diet ( according to our preference veg/nonveg ) which should contain adequate quantity of protein, carbohydrates, fats, vitamins and minerals. Our daily food which contains 1. cereals ( wheat, rice, soyabean etc. ), 2. Pulses ( arhar, moong dal etc. ), 3. egg, fish, meat, milk.  3. vegetables and 4. fresh and dry fruits if taken in sufficient quantities and daily 1/2 hour of exercise will definitely improve our immunity.         There is no particular dry fruit which is especially used to boost immunity.          Dal cooked in pressure cooker is better and retains its nutrients.