Composition: the window pane, blue bowl, and cut-off edges of the plate are distracting. I also find the silver plate itself to be a composition problem: all of the highlights and shadows make it a distracting element. It's dark behind the food -- is this a reflection of you? On the right, behind the lemon reflection is something that looks sort of like a camel's head.
To place more emphasis on the food, I would use a solid color plate -- especially for this food where you've got so little color. A vibrant blue, green, red, etc, plate would allow the food to pop right off! It would also not have the same reflection problem that the silver plate has.
I would get closer to the food. ("Wait, you said the cut-off edges of the plate are a distraction!") Yes, go ahead and get closer and cut off the edges of the plate: so that all I see in the frame is the plate and food -- nice and tight. Really show off the food and make it appetizing.
The diffuse window light is nice, but you're pointing the wrong way with it. The daylight is streaming in through the window and hitting the back of the food, as you've shot it. Put your back to the window/sunlight and you'll likely get a little more pop out of the colors. Or, try shooting with the window light streaming across the side of the plate.
I remember seeing somewhere that a "natural light photographer" is somebody who used flash once, didn't like the result, and decided to never use it again. The trouble is, well-used flash is really the key to making a dynamic photo that pops. I would start with just an umbrella or softbox to light the food. It'll add some pop, bring out more detail, and show off the food to make it more appetizing.
Have some extra flashes? I would maybe add a more harsh sidelight to bring out the texture in the whipped cream(?). Maybe use a rim light to light the back of the lemons and make the edge of them really pop off the plate.
Style the food. Get a spritz bottle of water and spray it on the cut open lemon so that it will cause little highlights and "sparkle" when you blast a flash on it. Make the whip cream into a fancy dollop with a big peak, or form it into quenelles. Would something like a mint leaf make sense for this dish? An extra splash of color, texture, and shape in such a simple dish would add a great extra element of interest.
For your next shoot, just try and focus on improving one or two things. Try using a solid color plate, and try moving the plate so that you can shoot with the window light at your side or back. Make step-by-step changes and you'll be able to see how each thing improves the photo. Changing everything all at once will make it hard to understand what specific changes helped with what aspect of the photo.