Cold Bulgarian soup with kefir, cucumbers, dill, walnuts and feta

• 4 garlic cloves peeled and minced
• 4 Persian cucumbers diced finely
• ¼ purple onion diced finely
• ½ cup shelled walnuts finely chopped
• 3 cups Kefir or 2 cups Greek yogurt diluted with ice-cold water
• 1 TB walnut or extra virgin olive oil

Toppings (choose any or all of the following):

• 4 radishes sliced finely
• 1 bunch dill chopped finely
• 2 scallions sliced into rings
• 2 tablespoons lemon juice
• ¼ cup feta or Bulgarian cheese
• Ice cubes
• salt to taste
• freshly ground pepper to taste