The phrase "half portion of" is correct and can be used in written English.
You could use this phrase in a sentence such as, "I'd like a half portion of the steak."
One of the pleasantest surprises was a half portion of Peking duck, easily shared by two.
For £4.75 (11aMon-FriMon-Fri) you can get a six-inch pizza and a half portion of salad.
For a first course, a half portion of pasta served nicely, but a few appetizers were noteworthy as well.
The maximum structural responses of models with rather shorter natural periods are often induced by the intensive motions existing mostly in the first half portion of ground motions.
One day I couldn't decide between the chicken Monterey and the avocado and seafood main-course salad, so I had a half portion of each.
In fact, Sema3E can be detected in the upper half portion of the neocortex by western blot techniques (Supplementary Fig. 3).
Half portions of several entrees are available, and there is a range of daily specials.
Half portions of pastas (which would be entree-size elsewhere) should also be seriously considered as starters.
You can order half portions of many dishes, including grilled chicken and fried shrimp, for 7.50 euros.
Half portions of pastas and salads, the size of full portions elsewhere, are an excellent idea, as is the sharing of appetizers.
