This is a GREAT question! As a taco shop enthusiast from San Diego, CA, I can recommend three:
- Mike's Tex Mex in Yokosuka or Fussa (affordable)
- Fonda de Madrugada in Shibuya/Harajuku (pricey).
- La Jolla Mexican in Hiroo
Not exactly 100% the same as SoCal Mexican food, but it definitely hit the spot.