Heat oil in a large saute pan on medium heat. Add onion and thyme to pan stirring for approximately 2-3 minutes. Reduce heat to medium low.
Cook onions, stirring regularly, for about 45 minutes or until soft and deep golden brown in color. If onions start to stick to pan you can add a tiny bit of water to deglaze the pan. When there is 10 minutes of cooking time left add the garlic.
While onions are cooking, combine sour cream, mayonnaise, chives, lemon juice, salt and pepper in a medium mixing bowl. Cover and place in fridge.
Once onions are caramelized, transfer them to a separate small bowl and place them in the fridge to cool.
When onions are cooled, combine them to the sour cream mixture. Stir until well combines and season with additional salt and pepper, if needed. Transfer to a serving bowl an serve with chips and/or veggies.