To create a smoky flavour pour ground coffee or tea and dried and ground spices over the coal. Afterwords close the grill lid and allow the flavour to set in the food. A slightly more complicated option is to create a tinfoil bowl, in which you pour a bit of water and add spices, and then place it on the coals. If the grill has a lid, you can place the tinfoil bowl on the grid. Evaporating water will create extra moisture and a pleasant smoky flavour. Another way to gain a very nice flavour is to place a whole onion on the coal.
You can create interesting flavour nuances to various foods by placing spices (rosemary, caraway, basil) or plant twigs (cherry, apple tree, raspberry, juniper). Place the twigs and spices in water to slow down burning and to create smoke.