In a mortar, mash the garlic with a few pinches of salt until a paste forms. If you don't have a mortar and pestle, use a deep cup and a cocktail muddler. Or, squish everything on a plate to make the paste. We can make it work!

Add the annatto, paprika, cumin, oregano, pepper and olive oil to the mortar; mash and mix together. Add the vinegar and half the lemon juice and mix again.

Rub the mixture on the chicken, including under the skin, then pour the remaining lemon juice into the bird’s cavity and insert the onion halves. Tuck the wings underneath the bird and let the chicken sit at cool room temperature for at least 1 hour or in the fridge overnight. (If the chicken is chilled, let it come to room temperature for about 30 minutes before roasting. I don't do this, but you should.)

Preheat the oven to 400°F.

Roast the chicken breast-side up for 30 minutes, then baste with the pan juices. If no pan juices have accumulated at this point, brush the skin with olive oil. Continue roasting the chicken, basting or brushing every 30 minutes, until its juices run clear and a thermometer inserted into the thigh registers 160°F. Depending on the size of the chicken, this will take 60 to 90 minutes.

Let it rest for at least 10 minutes or until room temperature. (I don't do this, but you should.)