Combine ingredients: In a medium bowl, whisk lemon juice, Dijon mustard, minced garlic, salt, and black pepper until well combined.

Emulsify with olive oil: Add in one tablespoon of olive oil and emulsify. You will see the mustard mixture thicken. Add in one more tablespoon and whisk until integrated. Continue twice more, adding one tablespoon at a time. When an emulsification has formed, pour the oil slowly while continuously whisking until the dressing is thick and delicious.

Taste and adjust: Taste and adjust the seasoning with additional salt and pepper if needed.