To prepare dressing:
Combine all ingredients except for oil & oregano in blender. Blend until smooth.
With blender running, stream in olive oil.
Add oregano and blend till mixed.
Heat oil in large skillet over med heat. Add prosciutto and cook until brown and crispy. Remove from pan with slotted spoon and drain on paper towel. Set aside.
In large bowl, toss the lettuce, onions, gorgonzola cheese, and crispy prosciutto bits. Lightly drizzle on dressing (start with a little, you can add more to your taste preference) and toss to combine.