Place the sliced cucumbers, avocado chunks, chopped parsley, olive oil, lemon juice, salt, and black pepper into a large bowl and gently mix until well combined. Serve right away.
4 medium cucumbers, sliced, 3 ripe avocados, cut into chunks, 3 tbsp olive oil, 3 tbsp lemon juice, 1 tsp salt, or to taste, ½ tsp black pepper, or to taste, ¼ cup fresh parsley, chopped