When I have to use a potato or cauliflower for cooking, I can never manage to retain the color of these vegetables. A friend told me this handy tip to keep the cauliflower white.
While you are boiling a new potato or cauliflower add a 1/4th of a lemon to the water in which you are cooking. This restricts the cauliflower from turning grey and keeps it white. You can keep this cooked cauliflower aside and then use it for any recipe that you have to make.
Use the same trick for a potato as well and get back to me with the results!