Second Flush Assam Tea harvested in the month of May and June in India is the best black tea for Chai. Fresh tea leaves are taken through a process called CTC (Crush Tear Curl) where leaves are processed through a series of rollers. The rolled tea leaves are then oxidized, dried, sorted and packed. The process of oxidation creates two distinct antioxidants for black tea- Theaflavins and Thearubigins. A term you’ll often hear with Black Tea is Orange Pekoe. Orange Pekoe is leaf grade teas that denotes a quality product.