Begin by thinly slicing the yellow onions using a sharp knife or a mandoline for uniformity. Aim for slices that are about 1/8 inch thick.

Heat a high-quality non-stick skillet over low heat and add a tablespoon of butter. Once melted, incorporate the sliced onions, stirring to coat. Cook for 30–40 minutes, stirring frequently, until they are a deep golden brown and sticky.

Reduce heat to medium-low and stir in minced garlic, soy sauce, and Worcestershire sauce. Cook for an additional 2–3 minutes.

Remove skillet from heat and let it cool for a few minutes. In a separate bowl, combine sour cream and cream cheese until smooth. Gradually mix in the caramelized onion mixture.

Transfer dip into an airtight container or serving bowl and refrigerate for at least 1 hour before serving.