Cucumber Onion Salad

INGREDIENTS

• 1/2 cucumber, very thinly sliced
• 1 celery, diced
• 1/4 onion, very thinly sliced
• 2 tablespoons lemon juice
• 2 tablespoons olive oil
• 2 tablespoons cider vinegar
• 1/2 teaspoon oregano
• 1/4 teaspoon minced garlic (or to taste)
• 1/2-1 teaspoon sugar (to taste)
• feta cheese (optional)