A torch used on any "weed" will cause the cells in the top growth to burst and that top growth then dies. This will not necessarily affect the roots, but if this is repeated often enough the roots, failing to get adequate nutrients, die.

freshfields, purslane is an annual plant and I doubt that it will be able to come back from the root system once you've 'fried' it. Annual root systems don't have much of a storage system.