Who sells the Super Taco that Jack in the Box used to sell?

Jack in the Box! No one but original Company can sell a food Item "exactly like" itself....

trademark and copyright law come into play and occasionally even patents and trade secrets

That said, any "Mom & Pop" restaurant that sells tacos can put together one with whatever ingredients you want. The size of the shell might be different but taste the same. If after eating you are still hungry, buy a second one :D