začiniti

1. (of food) to season; to spice
   Začinila je salatu uljem i sirćetom. — She dressed the salad with oil and vinegar.
   Supu sam začinio solju i biberom. — I seasoned the soup with salt and pepper.
2. (of a story, speech) to spice up
   Govor je začinio sa nekoliko dobrih šala. — He spiced up his speech with a few good jokes.

The imperfective is začinjavati; the seasoning is in the instrumental (začiniti solju).