This undoubtedly calls for a white wine with high acidy.
compliment the Tuna, French beans and romaine lettuce on the
plate. Though with this simple presentation I would be hesitant
to pair it with something too over powering, with the subtleness
of tuna a big "oaky" Chardonnay or Riesling might mask the
main component too much.
So I would consider a simple Italian white like a Greco di
Tufo. The largest and most prestigious producer in this region
is Mastroberardino. Also I might think of the Pinot Gris grape
grown here in the US, a couple of producers that I enjoy are
Chalk Hill and King Estate.