El Centro D.F. has some new neighborly competition in the table-side made-to-order guacamole business.  And this place packs its avocado dip with spicy serrano. Located just a few blocks away, the new and purportedly more authentically Mexican Tortilla Coast opens Monday at 1460 P St. NW. Washingtonian has photos. Metromix hit up last night’s opening party.