Marinate the chicken: In a large bowl, mix the olive oil with the rosemary, thyme, oregano and ground cumin. Add the chicken and toss well. Cover and refrigerate for at least 2 hours or overnight.
Meanwhile, Make the Harissa: In a small skillet, toast the cumin, coriander and caraway seeds over moderately high heat, shaking the skillet a few times, until the spices are fragrant, about 2 minutes. Transfer to a spice grinder and let cool completely. Grind to a powder.
In a blender, combine the roasted peppers with the chile, garlic, olive oil, lemon juice and ground spices and puree. Season the harissa with salt.
Light a grill. Thread the chicken pieces onto 8 metal skewers. Season with salt and grill over moderately high heat, turning, until nicely charred and just cooked, about 14 minutes. Serve the skewers with the harissa and hummus.