This quickie will show you How to Draw a Lemon using Inkscape.
Start out with a Circle.
Make the Color yellow.
Make a Duplicate of the circle and Dynamic Offset it to be slightly smaller.
Make the duplicate White.
Make another Duplicate the same way, slightly smaller than the previous.
Give it a lighter Yellow color.
Add nodes to the new Circle until it has 16 Nodes.
Select every other Node starting with the top node.
Then Scale them slightly, while holding the SHIFT key, to move them all inwards toward the center.
It should start looking like the picture below.
Create a white Circle in the very center.
Then make a vertically long Rectangle that runs from the New circle to the other white of the Lemon.
Move the Rotation center-point of the Rectangle downwards to the very center of the white Circle.
Duplicate the rectangle and Rotate it clockwise about 45 Degrees.
Continue to do this until it looks like the picture below.
Now Select the center circle and all the rectangles you made and Union ('CTRL' + '+') them together.
With those still selected, also select the yellow circle, just underneath, you made earlier and take the Difference ('CTRL' + '-') of them.
The yellow Circle should now be broken into 8 arrowhead shaped pieces, but still intact.
Select everything so far and Union them together.
Then Scale it a little bit horizontally.
Now we'll start on the Body of the lemon.
With your Pen Tool create a shape like the one below, making sure it fits inside the shape you made.
(The 2 Nodes on either side of the right-most corner node are important for getting the correct shape)
Smooth all the nodes and Lower the shape to the back.
Let's work on the Shading.
Create 2 black Shapes that follow the contours of the lemon's body.
Smooth those nodes (except corner nodes).
Then set the Opacity and Blur to your liking.
I removed the Stroke and we have a finished Lemon!
We can go a bit further though.
Make a copy of the Original slice (not scaled) as well as the first Circle you started with.
Scale them both vertically.
Then put the Lemon slice ontop the other circle.
Then you'll have Lemon slices you can stack as well as a Lemon body!