At first, I was tempted to use bold vector graphics, or otherwise stock photography. I think close-up photographs are often used (certainly in supermarkets, or in the Spar at the end of my street)
I found these via Bing search engine, they are all licensed by creative commons.
But I wanted to have a go at doing something a bit different, and maybe creating graphics for a Farmers Market type of greengrocer. I looked at a variety of illustration styles. These are lovely, but maybe not really suitable for large display. The really stylised ones seem better suited to packaging or recipe books.
This led to me to buy some pastel pencils to draw a picture of an apple and a pepper. I haven’t used traditional materials much, especially not with colour so this was a bit daunting. but I really wanted to give it a try.. I decided on single fruit and veg for maximum clarity. The pepper and apple are a simliar size and shape, in complementary colours, which i’m hoping will create balance between the two pictures.
The paper is actually white (I don’t know why pastels are usually on coloured paper?) but it still photographed as grey, so I had to remove the background in photoshop, and replace it with white, which I think looks cleaner. They are slightly stylised, but I was aiming for crisp and clear.
Then I chose a font I liked and kept the wording very simple. Whether they would stand out enough, is still something to ponder, but I hope that having a large picture of single fruit, combined with coloured text, would catch the eye.