Make seasoning: In a blender, whirl onion, ginger, and oil until smooth. Add salt and pepper. Pour mixture into a resealable plastic bag and add meat. Seal bag, turn to coat meat, and chill at least 4 hours or overnight.
Make dry rub: Whisk all ingredients in a bowl and set aside. (Save 1 tsp. for Spiced Yogurt Sauce.)
About 1 hour before cooking, let meat come to room temperature. Soak 8 (12 in.) bamboo skewers in water at least 30 minutes, or use metal skewers. Thread about 6 chunks of meat (with seasoning paste) onto each skewer.
For charcoal, ignite a full chimney of half mesquite lump charcoal and half mesquite charcoal briquets on firegrate of a charcoal grill. When lit, 20 to 25 minutes, arrange coals in an even layer and set cooking grate in place (fire should be 400° to 450°). For gas, heat a grill to medium (400°).
Oil cooking grate, using a wad of oiled paper towels and tongs. Grill meat, covered and turning once, until medium-rare, 6 to 8 minutes total. Transfer to a rimmed baking sheet. Sprinkle meat heavily on all sides with dry rub (you may have some left over). Let meat rest 2 to 3 minutes.
Set skewers on a platter and drizzle with some yogurt sauce. Scatter with smoked paprika and herb sprigs. Serve more sauce on the side.
*In Ghana, cooks pound and then sift peanuts. Here, powdered peanut butter such as PB2 is widely available at well-stocked grocery stores. Find almond meal in the baking aisle; toast in a 350° oven until light golden, 12 minutes.