We'll start by opening a new document 800 X 600 px.
Foreground color: Black.
Do not name layer. Leave it as "Background".

We'll also work with this image of a hamburger, provided by
pxleyes for a contest. The image is 800 X 600 px.
You can download it, by clicking the right side of your mouse over the picture.
Save picture as...
Save it in a place where you can have access to it.

Making the branches.

Use the Polygonal Lasso Tool (L).
Make a selection of a piece of meat. Copy (C) and Paste (V).
Name new layer, "Branch".

Duplicate this layer to make a copy of meat. Join two pieces together. Merge new layer down. Do not change name.

Use Filter - Liquify - Warp (W).
Brush Size 165
Brush Pressure 50
Try to give your branch this form.

Copy (C) and Paste (V) some pieces from the main branch. Four or five copies will be fine, it depends how many branches you will use in your main branch.

Remember that every time you copy and paste and object, a new layer will appear. Name new layers, "Branch1", "Branch2", "Branch3", "Branch4", etc.

Use Liquify Tool (Shift + Ctrl + X). This time use a smaller brush. A 65 size and a pressure of 50.

Putting the branches together.

You will add the smaller branches to the main branch.
If for any reason the areas where the branches join, does not look good, use a Spatter Brush 24, make it smaller 15 px, with opacity of 50 percent. Start smudging the areas a little, until they look like they are part of the main branch.

After you are happy with the result, you can merge down the layers, "Branch 1, 2, 3, 4,", etc. to form one layer. Name this layer "Branch".

How to make the leaves.

You can use the image of hamburger again to Copy (C) and Paste (V) a selection of the meat to form the leaves.

Duplicate your selection three times.
Merge the three layers down. Name new layer, "Leaf".
Use the Clone Stamp Tool (S). Clone all the lines in the middle of meat.

Use the Eraser Tool (E) to erase the border. Form a rounded shape.

Leaf Color:
Green.
Image - Adjustments - Color Balance
Midtones: + 60
Highlights: + 20

We'll make more leaves from this transformed piece of meat.

Use the Liquify Tool (Shift + Ctrl + X).
Warp Tool (W).

Use a Brush Size: 50
Brush Pressure: 50

Start warping around, until you get the shape shown in detail in this step.

Make at least 8 copies of main leaf. Copy (C) and Paste (V).
Every copy will open a new layer. Name layers, "Leaf1", "Leaf2", "Leaf3", etc.

Use the Transform Tool (T).
Make some small leaves. Do not worry about having those many layers, you'll merge them down when you place all the leaves over the main branch.

You can use the Liquify Tool (Shift + Ctrl + X). Warp Tool (W), to give a different shape to some of the leaves, in this way, they won't look the same.

You should have something like this.

Start placing all the leaves over the main branch.

You can add more branches to the main branch if you want. It is up to you. Use the Burn Tool (O) to burn a little around the areas where the leaves overlap eachother.

Merge down all the layers named, "Leaf1, 2, 3, 4,", to form one layer. Name new layer, "Leaves".

Forming the Flowers.

The flowers will be made of a small piece of onion.
We just need to make a petal to form a flower.
In this step, we'll learn how to do it, and for this, we will the image source of the hamburger again shown in step 2.

Follow the steps given in the image.

We'll form the petal.

From the meat of the hamburger, make a jagged selection, Copy (C) and Paste (V).
Duplicate layer again and colorize it.
Image - Adjustments - Color Balance
Midtones only.
Color Levels: Magenta -100

Move the colorized meat to the center of the petal.
Merge down layer. Name new layer, "Petal".

Delete the layer with the non-colorized piece of meat. You do not need it any more.

For this step, you will read and follow the directions and tips given in the image. This is an important step. If needed, read it twice.

We'll put the flowers together. This is a very important and necessary step. We will duplicate the flower we made in the step before. Just by copying and pasting selected layers to form the group of flowers. We'll place the flowers over the branches.

This is our final step. The flowers are placed over the branches, leaves look good too, and our final image has been accomplished! I hope you enjoyed this tutorial. I appreciate your patience to learn something new. Good luck to you all!