Put the onions, with the skins on, in boiling water for about 3 minutes, or until just barely cooked. Drain and cool, and then remove the skins.
In a shallow bowl large enough to hold the chicken pieces, mix together the chopped herbs, garlic, lemon juice, and olive oil. Marinate the chicken at room temperature in this mixture for half an hour to an hour, or, alternatively, in the refrigerator for up to 2 hours.
Return to room temperature.
Using 4 metal or water-soaked bamboo skewers, make the kebabs, alternating the chicken, pearl onions, and bread cubes. Insert sprigs of the stalks of rosemary or thyme between the other ingredients. Brush each kebab with the marinade, and sprinkle with salt and pepper.
Preheat the oven to 400°F (200°C).
Briefly sear the kebabs on a hot grill, turning very gently, then place them on a pan and bake in the oven for about 10 minutes. Remove from the oven, tent with foil, and let rest for 5 minutes.