Start by mixing a marinade for the chicken and prawns. In a large bowl mix together the lime juice and zest, chilli, cumin, garlic, fresh coriander, honey, olive oil and season well with salt and pepper. Divide into 2 bowls and use to marinate the chicken and prawns separately for 30 minutes. Meanwhile, prepare the vegetables. Thread the diced peppers onto skewers separately. Also, do the same with the onion onto a separate skewer. Season them all with salt, pepper and a little olive oil. Also, make a dressing by mixing together the yogurt, garlic, olive oil, fresh coriander and season well with salt and pepper. Place the dressing into the fridge to chill. When ready, thread the prawns onto skewers and the chicken separately onto more skewers. BBQ the prawn, chicken and vegetable skewers on both sides on a hot grill for 5-10 minutes until brown and charred along the edges. To serve, arrange the skewers onto a large serving board with the dressing in a bowl on the side, extra lime wedges and the warm grilled tortillas.