We were following an Indian recipe today that called for sauteeing the main ingredient in mustard oil. We didn't have any on hand, but got to thinking, mustard oil is made by pressing mustard seeds, and mustard is a brassica. Canola oil is made by pressing rape seeds, which is also a brassica. Brassicas tend to interbreed a lot.
How different are mustard oils and canola oils? How does one go about substituting one for the other? (The recipe we used called for a large amount of freshly ground mustard seed to be added later, so in the end I guess the flavors would be similar).