Peel the onion and cut into feathers. Peel the sweet pepper from seeds and partitions and cut into strips.
Fire up the coals. When they are well flared, put a frying pan on the grate, add olive oil and put onions and peppers. Salt, pepper, add oregano and fry, stirring, 15-20 minutes.
When the coals are covered with light ash, spread the sausages on the grill grate and fry them until golden brown on all sides. Transfer the cooked sausages to a board and cut into slices diagonally.
Warm the tortillas or pitas on both sides and transfer to plates.
Place sausages and roasted vegetables on each tortilla. Sprinkle with crumbled feta if desired.