A 55-year-old man attends your general practice for review. He has had three office blood pressure readings over the past month around 158/96 mmHg. Today, after 5 minutes seated rest, his averaged blood pressure is 160/98 mmHg. He has no diabetes, chronic kidney disease or known cardiovascular disease. BMI is 31 kg/m² and routine blood tests are normal. According to current Australian hypertension and CVD risk guidelines, what is the most appropriate initial pharmacological approach in addition to lifestyle modification?