Preheat the oven to 200°C (400°F).
In a mixing bowl combine 2 sliced onions, the quartered lemon, thyme, garlic cloves, bay leaves, a splash of olive oil and a pinch of sea salt and black pepper; toss to coat.
Stuff the seasoned mixture firmly into the chicken cavity.
Truss the chicken using the kitchen twine: centre the twine under the tail, bring the ends up, cross and wrap around each drumstick, pull tight, knot and trim excess.
Lay the remaining sliced onions in the bottom of a roasting tray and place the chicken on top, breast up (back and wings facing down).
Rub the chicken lightly with olive oil and season liberally all over with sea salt flakes, smoked paprika and freshly ground black pepper.
Roast at 200°C (400°F) for 15 minutes, then reduce the oven temperature to 180°C (350°F) and continue roasting for about 60 minutes.
About halfway through the remaining roast time, baste the chicken with a little olive oil to keep the skin moist and help browning.
Check doneness by piercing the thickest part of a leg near the joint; juices should run clear, or use a meat thermometer inserted into the thigh reading 75°C (165°F).
Remove from the oven and let rest a few minutes before carving, then serve.
