Finely chop the basil and parsley. Put the kefir in a container and mix with the finely chopped herbs, pepper, salt, chili powder, garlic, onion, bay leaves and juniper berries.
Cut the meat into 4 x 4 cm cubes. Then roll in the marinade, mix in the thyme sprigs and cover in the refrigerator for at least twelve hours, or better 24 hours.
Preheat the grill to 200 degrees.
Remove the pieces of meat from the marinade and place on 3 - 4 grill skewers. Grill meat skewers and turn a little every four minutes. After approx. 25 - 30 minutes they should have got a light tan and can be removed from the grill - done.