mixing algorithm of tea bag flavors

To begin the sequence, choose a random tea flavor. For the next tea bag, choose randomly from all the flavors except the one we have just chosen. For example, if the first tea flavor is A, choose between B and C.

choose from (A, B, C)
  [A]
choose from (B, C)
  [A, C]
choose from (A, B)
  [A, C, A]
...

If you have more than three tea flavors, you may want to go back to more than one position. If our flavors were (A, B, C, D), we would look back two places.

choose from (A, B, C, D)
  [A]
choose from (B, C, D)
  [A, D]
choose from (B, C)
  [A, D, C]
choose from (A, B)
  [A, D, C, A]
...