We do it slightly differently here in the U.S. (still talking about onions, aren't we?) When we pick the onions, (usually a Walla-Walls type yellow onion variety, they are about 3 to 4 inches in diameter. We pick them with enough neck to tie them together, as others have suggested, but then (this is usually late September to early October) I hang them on a south facing wall outside being sure that they don't get rained on. I leave them there at least 2 weeks and then store them, still hanging as others have suggested. The drying gives an expected 4 months at least,of storage. We often have them last through the winter...