1/2 stick (1/4 cup) unsalted butter
3/4 cup farinha de mandioca* (manioc flour; not toasted)
1 1/2 cups chopped onion
5 garlic cloves
7 bottled red malagueta peppers**
1 teaspoon sugar
1 teaspoon cider vinegar
1 tablespoon plus 1/2 teaspoon salt
3 tablespoons olive oil
3 (1 1/2-pound) frenched racks of lamb (8 ribs each), trimmed of all but a thin layer of fat
3 tablespoons finely chopped fresh flat-leaf parsley
Special equipment: an instant-read thermometer
*A coarse, granular meal made from grated cassava root, farinha de mandioca is available at some Latino markets and Sendexnet (866-736-3396; sendexnet.com).
**Fresh malaguetas are difficult to find in the U.S.; instead, look for them bottled in vinegar or in the clear, strong brandy called cachaça, available at some Latino markets and Sendexnet (866-736-3396; sendexnet.com).