A lemon wedge on its rind

Use a half-moon shape and radiating lines to draw a lemon wedge. A doubled rind edge gives the slice thickness with very little tone.

A way into the drawing

Draw the cut face
Sketch a broad half-moon shape with a straight top and curved lower edge. Keep the face slightly angled rather than perfectly flat.
Give the rind thickness
Add a second curve beneath the face and connect the ends. This narrow strip makes the wedge feel like a solid form.
Divide the segments
Bring a few lines from near the upper middle toward the curved edge. Add small seed marks, a few loose rind marks, and a faint shadow underneath. Leave the flesh white.

A small thing to tryLet the segment widths vary a little. Their overall direction matters more than identical spacing.