
It's really quite simple and the only tool you need is a ring mold. If you don't have any and you're interested in working on presentation, I strongly recommend getting a set like this. You will find a hundred and one uses for it.
Here are some suggested ingredients for the vegetable salad that make up the bulk of the garnish, but you should use whichever vegetables you have on hand or whatever looks good at the market that week.
1 small cucumber, cut into a small dice
1 yellow summer squash, cut into a small dice
1 red bell pepper, cut into a small dice
1/4 bunch of cilantro, chopped finely
Salt and pepper
1 avocado
Make the vegetable salad by combining the cucumber, squash, bell pepper and chopped cilantro. Season with salt and pepper.
Cut the avocado in half and peel. Place the avocado cut side down on a cutting board and slice very thinly.

Spray the ring mold lightly with cooking spray so the avocado won't stick to the mold once you're ready to remove it. Place the thin slices of avocado in overlapping layers around the ring mold as pictured above.

Gently spoon the vegetable salad into the avocado ring. If desired sprinkle a bit more cilantro and salt over the top of the salad.

Remove the ring and make sure the salad is holding its shape.

Pour in your finished gazpacho and enjoy!