1. Combine yogurt, turmeric, chile powders, cumin, coriander, garam masala, salt, vinegar, lime, ginger-garlic paste and oil in a medium bowl and thoroughly mix.
2. Slice the tri-tip or flank steak into thin strips. Season the meat liberally with kosher salt. Let steak sit 10 minutes so salt incorporates into the meat and then liberally apply the marinade, about ¼ cup. Reserve leftover marinade for another use. Let meat marinade for at least 30 minutes and up to 6 hours.
3. Skewer the meat, leaving space between each piece to allow even heat distribution. Fire up your grill until very hot, then cook for 2 minutes per side for medium rare, and 3 to 4 minutes per side for higher levels of doneness. Remove from heat and tent with foil. Once meat has cooled slightly, slide off of skewers.
4. Lightly butter dinner rolls and toast on the grill until lightly browned. Spread each roll with 1 teaspoon mayonnaise, add kabab strips and julienned onion, and top with cilantro and mint.