Whisk the olive oil with the salt, pepper, cumin and the leaves of the thyme, after reserving several sprigs. Slice 1 1/2 lemons and place in a casserole in a single layer. Cover with the onion, peeled and sliced, and then the garlic, peeled and roughly chopped. Cut the backbone from the chicken (with two lengthwise cuts, one on either side of the bone). Spread the chicken and lay it skin-side down in the casserole. Brush with half the olive oil mixture, tuen it over, pat the skin dry with a paper towel, and brush with the remaining mixture, Pour the wine around the chicken. Roast in a 400° oven, basting occasionally, for 1 1/2 hours or until tender. Remove from oven and allow to rest for 15 minutes.

Squeeze the juice of the remaining half lemon over the chicken, cut into pieces, and serve.