Preheat oven at 350℉
Place the garlic cloves in a small oven-proof bowl with one tablespoon of the oil.
Cover with aluminum foil and roast, covered, until tender, about one hour period; then cool.
Squeeze the garlic meat from its husks and reserve. In a large saucepan, heat the remaining oil over medium to high heat, add the onion, and cook until soft.
Add the stock and bring to a simmer.
Add the clams, cover, and cook until they open, 5 to 10 minutes.
Add the garlic, orange zest, lime juice, salt, and pepper.
Stir and taste for seasoning. Serve immediately, passing the lime wedges and jalapeno at the table.