Pass your free of weight foot, inside edge in contact with the floor, behind the heel of your standing/pivoting foot, and continue to a step to the side around your partner.
If you are in the San Francisco Bay Area and want to learn to dance Tango, you can:
I was born in Argentina. Through my family and the community that saw my upbringing, I have been intimately involved with the culture of Tango all my life, and have been an Argentine Tango dance performer, choreographer and instructor for over 30 years. I profoundly love Tango dancing, music, and culture, particularly that of the Golden Era. I am a milonguero.