Preheat the oven to 200°C (400°F).
In a mixing bowl combine 2 of the sliced onions, the lemon wedges, fresh thyme, garlic cloves and bay leaves; add a good splash of olive oil and a pinch of sea salt and freshly ground black pepper, then toss to coat.
Stuff this mixture firmly into the cavity of the chicken.
Truss the chicken using the kitchen twine: place twine under the tail, bring ends up and cross, wrap each end around a drumstick, pull tight, cross again and knot; trim excess.
Lay the remaining sliced onions in the bottom of a roasting tray and place the chicken on top, with the back and wings facing down.
Rub the outside of the chicken lightly with olive oil and season liberally with sea salt flakes, smoked paprika and freshly ground black pepper.
Roast the chicken at 200°C (400°F) for 15 minutes, then reduce the oven temperature to 180°C (350°F) and continue roasting for a further 60 minutes.
About halfway through the second roasting stage, baste the chicken with a little olive oil.
Check for doneness by piercing the thickest part of the leg near the joint; the juices should run clear when the chicken is cooked through.
Remove the chicken from the oven and rest briefly before carving, then serve.