You may use a food processor or blender. Start by placing the avocado pulp, mayonnaise, vinegar, buttermilk, lime juice, garlic powder, onion powder, cumin, dill, sugar, salt and pepper in container of the blending device you will be using.
Blend until smooth, scrapping down the sides occasionally with a spatula.
With lid on and blender running, slowly drizzle in the olive oil.
Then is the dressing needs to be thinned a bit, using the same process, drizzle in water 1 tablespoon at a time until you have reached the desired consistency.
Taste and adjust salt and pepper or any other seasonings, if desired.