1 – Melt 1 cup butter with ¼ cup canola oil on low heat.
2 – Place 1 tablespoon Dijon mustard, ½ cup egg yolks (about 9 yolks), and ¼ teaspoon salt in a food processor. Run until slightly fluffy.
3 – With the machine running, slowly drizzle the almost-hot butter mixture into the egg mixture. If too thick, add a small amount of warm water. Season to taste.