Let T be the taco, B the burrito, MP the mexican pizza, R the rice, and N the beans.
For the main course we can have the first three.
----- T
------ B
-------MP
Each main course comes with the two sides. So an R branch and a B branch go to each of the taco, burrito, or pizza.
-----T---------R or N.
We expand it to
--------T-----------R
---------------------N
And we repeat it for the rest.
Thus, the tree diagram is
----- T --------R
-----------------N
-----B---------R
-----------------N
----MP--------R
----------------N
