Combine shallot, garlic, mustard, vinegar, and water in a large bowl and whisk to combine.
Whisking constantly, slowly drizzle in olive oil.
Alternatively, place all ingredients in a tightly sealing jar, seal, and shake vigorously until emulsified.
Season to taste with salt and pepper.
Vinaigrette will keep in the refrigerator for up to 2 weeks.
