Leaves and immature flowers of a kra pao or holy basil plant are used in Thai cuisine, especially in making a Thai popular dish names pad kra pao.
Holy basil or kra pao in Thai, also known as tulasi, tulsi or sacred basil, is an aromatic plant in the family Lamiaceae, native to the Indian subcontinent and widely cultivated throughout the Southeast Asia. It is 30-60 cm (12-24 in) tall with many small-hairy branches and green or purple leaves usually slightly toothed. Its leaves are strongly scented. The flowers are either greenish or purplish in elongate racemes in close whorls. Source: https://en.wikipedia.org/wiki/Ocimum_tenuiflorum
In Thai cuisine, the holy basil leaves and flowers are used in many menus, especially pad kra pao, a very spicy dish made by stir-frying meat with minced garlic cloves, minced fresh hot chilies and the holy basil leaves (and sometime immature flowers) and often season with oyster sauce, light soy sauce, dark soy sauce and sugar, very popular in Thailand. Some Thais also love to add the leaves and immature flowers into tom yum soup, tom saab soup, kaengpa curry, etc. in a final step to add additional aroma.