Grilled Apricot-stuffed Leg of Lamb

boneless leg of lamb (4 to 5 lbs.) butterflied and trimmed of excess fat

coarse kosher salt, divided

plus 3 tbsp. olive oil, divided

small onions, roughly chopped (about 2 1/2 cups)

garlic cloves, roughly chopped

ras el hanout (see Notes)

to 1 3/4 cups dried apricot halves, preferably Blenheim