Website should list simply the amount of rice or similar commodity one can buy in local market of that country. Although even this will vary widely for large countries like India.
The problem is that you have to pick a commodity that is actually the same 'value' globally, which is very difficult. For example, rice is probably worth much less in Asian markets because it is grown so much there, as opposed to other regions which may have to import it, imposing additional costs for the transportation.
That's why poverty line is different amongst regions. What I want to know is if someone is able to buy same amount of rice in one country at poverty line as other countries or how much does it vary.
My point was that the relative value of goods could change. Even if someone in Ireland cannot buy as much rice as someone in India maybe they could buy more potatoes, because potatoes are easier to grow in Ireland while rice is easier to grow in India. If we want to use food as a metric, we would probably want to use some abstract measure of nutrition (maybe $/calorie).
