In a food processor, whirl egg yolks, 2 tbsp. lemon juice, mustard, sugar, 1/2 tsp. salt, and a few grinds of black pepper. With motor running, pour in olive oil and canola oil; mixture should be thick and shiny (you may need a little more or less canola oil).
Add lemon zest then salt and lemon juice to taste. Chill until cold.