As the temperature outside soared into the 80s,  Joseph Urtuzuastegui hunched over a blazing cooktop in the back of El Corazón food truck parked on Spring Street near the Cross Insurance Arena. “This is where it is hottest,” said the 52-year-old, motioning to the barely 1 inch between his bandanna-wrapped head and the truck’s ceilings. Still, he insists, there’s no place he’d rather be than cranking out tasty entrées for an ever-increasing lunch line. After spending most of his career in sales, Urtuzuastegui and a few of his family members opened the truck in 2013. Urtuzuastegui, who now lives in Cape Elizabeth but is from Arizona, said he loves when customers come to the back of the truck to watch him cook in the tiny space where he churns out tacos, burritos, tamales and other authentic Mexican goodies. “That’s what really keeps me going.” he said. “I just love the hustle and bustle of it.” The hardest part of the job – which nets him a salary of around $3,000 to $3,500 a month – is sourcing authentic ingredients that are also fresh, such as the cheese he uses that he has shipped from Mexico.