In your skillet, heat the olive oil over medium-high heat. Once hot, add the sliced green onions, leek, and shallot. Sprinkle with Kosher salt and black pepper.
Cook the onions for about 5-7 minutes, stirring occasionally, until they are soft and have developed a nice char. You want them to be golden brown, adding that smoky flavor to your dip.
Once the onions are charred, add the grated garlic to the skillet and cook for an additional 1-2 minutes until fragrant. Remove the skillet from heat and let the mixture cool slightly.
In a mixing bowl, combine the mayonnaise, sour cream, lemon zest, lemon juice, and chopped fresh thyme leaves. Stir until well blended.
Add the cooled charred onion mixture to the bowl with the creamy base. Mix until everything is evenly distributed. If the dip is too thick for your liking, you can add a splash of milk to achieve your desired consistency.
Taste the dip and adjust the seasoning if necessary. You may want to add a bit more salt, lemon juice, or even more thyme depending on your preference.
For the best flavor, let the dip chill in the refrigerator for at least 30 minutes before serving. This allows the flavors to meld beautifully. Serve with your favorite chips, crackers, or fresh veggies. Enjoy!