I would not call a 90x110cm Elinchrom softbox “portable”, however I set for myself the limit of one light source or when I want to shoot food outside of my studio, and albeit I tried and get the results that I wanted with a beauty-dish reflector (smaller and sturdier), I decided I would not settle for less than my biggie.
However, since I still need something to fill up the shadows a bit, I prepared some foam board.
Inside the softbox I used the golden reflector for warm light. In order to achieve some colour contrast and fill the shadows with cooler light, I prepared my foam core boards with some blue paper stuck on it. I also added some aluminium for extra reflection.
My softbox was placed hanging above the food, slightly inclined, so that most of the lighting surface would be “behind” the food, and lower.
In the end, this is what I got (Fujifilm X-T1, Fujinon XF 35/1.4 @ f/7.1):