Place the garlic, mustard, and egg in the bowl of a food processor fitted with a blade attachment. Process until evenly combined, about 10 seconds.
With the motor running, slowly add the olive oil in a thin stream, followed by the grapeseed or vegetable oil, until completely combined, about 2 minutes. Stop the processor, add the lemon juice, season with salt, and pulse until thoroughly mixed. Stop and scrape down the sides of the bowl with a rubber spatula, then pulse until all ingredients are evenly incorporated.
Let sit for at least 30 minutes before using. Refrigerate in a container with a tight fitting lid








