Three ingredients to make a delicious olive oil perfect for vinaigrette, dipping, sauteing, or...
Extra virgin olive oil (though plain old slutty olive oil would work too,) yellow onions (Vidalia-type sweet onions are too mild,) and Jane's Krazy Salt (sea salt would be just fine) are all you need.
Slice the onions, put them in a shallow pan with about a half an inch of olive oil, flip the slices to make sure they're well-coated, sprinkle with salt. Put in a 350 degree F oven for about an hour till they are beginning to brown and smell wonderful.
Let cool a bit then strain. The roasted onions will be good in a quiche, on a pizza, in soup, on bruschetta . . .
The oil, combined with basalmic vinegar and a little salt, makes a delicious, rich vinaigrette -- perfect for a plain green salad, incredible when you add fresh fruit (pears, for example,) nuts (pecans or almonds,) and gorgonzola or goat cheese to that salad.
Two big cooking trays and four onions yielded about a quart and a half of oil. The oil is a little cloudy -- that's the flavor -- and it keeps unrefrigerated for several weeks. Of course you can refrigerate it but we tend to use it up fairly quickly.
This was a serendipitous discovery when I was roasting onions for some recipe or other and decided to try the residual oil on a salad.