1. Chop the stoned avocado into small pieces.
2. Season both sides of the tomato slices with salt and pepper.
3. In a plate, lay the tomato slices in a single layer.
4. Chop the garlic clove and mix with a little salt. Mince this mixture,with the flat side of a knife.
5. In a bowl, mix the crab meat, chopped avocado,sour cream,half of the chopped basil leaves and chopped green onions.
6. Cover the bowl with a cling film and put it inside the refrigerator, to chill.
7. Cut the seasoned tomatoes into two halves and put them in a salad bowl.
8. Drizzle red wine vinegar and olive oil over the tomatoes.
9. Add the minced garlic, feta cheese and the remaining chopped basil to the tomatoes and toss the mixture , gently.
10. In a cake mold, fill the chilled crab mixture and press it in tightly, with the back of a spoon, for the desired shape to form.
11. In a serving platter, turn out the chilled crab salad and place the seasoned tomatoes around it.
12. Pour the residual liquid ,onto the tomatoes,as a dressing.
14. Serve the salad garnished with chopped green onions and cilantro leaves.