2 Tbsp. tomato paste
1 Tbsp. ground coriander
¼ cup toum
3 Tbsp. vegetable oil, plus more for grill
1¼ lb. skinless, boneless chicken thighs
Extra Toum
Pickles
Working one at a time, slice chicken thighs in half lengthwise and season generously with salt. Add to bag with marinade, seal bag, and massage marinade into chicken. Chill at least 3 hours and up to 12 hours.
Let chicken sit at room temperature 1 hour before grilling.
Prepare a grill for medium heat; oil grate. Thread chicken onto skewers, folding pieces back and forth accordion-style so they pile onto themselves (it should be about 3 strips per skewer). Grill, turning occasionally, until browned and beginning to char in spots, 10–12 minutes.
Serve chicken on top of pitas, with pickles and reserved toum alongside.