preheat grill pan or gas grill to medium heat. cut the kernals from the cob reserve 1/2 cup for a garnish an put the rest in a bowl. put 2 of the cobs back on grill an cook, turning, until light charred. scrape all the cobs fimlt with a knife to extract the milky liquid an add it to the kernels in bowl. break the 2 grilled pieces of cob into pieces an set aside.
melt the margerine in a lrg saucepan over med heat. add the onion an cook, stirring, until softened an translucent, aboutb 5 min. season with salt an pepper, add the vegtable stock, corn kernels, milky liquid, an grilled cob pieces to the saucepan. bring it to a boil, cover, an reduce heat to simmer. cook till the corn an onion are very soft, about 15 min. remove the cob pieces an discard. working in small amounts, puree the mixture in a blender an transfer to a clean saucepan add half an half an warm the soup till it thickens add a bit more half an half until you reach the thickness you want in the soup. taste an adjust seasoning. serve