Looks like a nice arrangement but I think the composition would be more stronger if you pulled back a bit more to show off the sashimi. Sounds odd but I am having trouble finding where my eye should settle and focus on. The blur of the green in the forefront center and the orange tones of the fish right behind it (some are in focus but the ones to the front are not) draw attention away from where the camera seemed to focus on the center of the dish. Pulling back a few inches would help the viewer appreciate the dish as a whole rather than the real close up view. b]OR[/b] you could increase the aperature (14 or higher) and adjust the shutter speed accordingly to a slower one to allow correct exposure to achieve a greater depth of field so that foreground and background are in nice focus. But it also means that with the slower shutter speed you will need to use a tripod to avoid blur - but the positive is that you will get a nice crisp shot of the full image. My taste buds have just now been getting into some sushi's but have not tried sashimi...that may have to be next on my list:-)
I love the lighting, colors, and addition of the flower. It looks light and healthy. I'm not sure what's in the front though, green cylindres... the vertical one could have been removed and the piece would be perfect.
I do enjoy good sashimi. You have a plate that obviously was prepared to be visually pleasing, but the capture of the image makes it fall. Dof is too shallow with no real focus or main point of interest. The flower stands out, but I wouldn't say that was a good thing. I think from a different angle , with more in focus you would have had a stronger image. Bet you had a wonderful meal though.
I like your food placement and composition. I'm however not at all liking the blurred foreground. To me having that sharp is essential to drawing in the attention. I wonder if you could have either used a larger depth of field, or maybe used some focus stacking techniques.