Special equipment: kitchen twine
For the lamb: Preheat the oven to 250 degrees F.
In a small bowl, combine the salt, pepper, coriander, cumin and fennel.
Drizzle the olive oil over both sides of the racks of lamb, then evenly apply the dry rub all over the lamb.
Using a sharp knife, make cuts between each of the rib bones on the back sides of the racks to allow the straight racks to be flexible and formed into a crown.
Tie the 2 racks together where they meet. Lift them so that the bare bones point upward and fashion them into a crown, then secure by tying twine around the bottom and midsection.
Place the crown roast onto a rack set in a rimmed baking sheet.
Roast until a thermometer inserted into the meat (avoid touching bone) registers 110 degrees F, 50 minutes to 1 hour.
For the pesto: Into the bowl of a food processor fitted with the blade attachment, add the mint, cilantro, almonds, salt, green onions, garlic and chile. Pulse, scraping down the sides of the bowl with a rubber spatula as necessary, until finely chopped. With the machine running, add 3/4 cup of the olive oil in a steady stream.
Pour the pesto into a bowl. Add the remaining 3/4 cup olive oil and the lemon juice. Season to taste. Cover with plastic wrap and set aside, or refrigerate (bring to room temperature 30 minutes prior to serving the lamb).
Remove the lamb from the oven and raise the oven temperature to 500 degrees F.
Place a sheet of foil over the bones to keep them from burning. Roast the lamb until a meat thermometer inserted into the thickest part of a chop reaches 125 degrees F for medium-rare or 135 degrees F for medium, an additional 10 minutes. Tent the lamb with foil and allow to rest for 10 minutes. Remove the twine and carve into chops; serve with pesto on the side.