BEFORETop Chef” glamorized bacon battles and squash showdowns, Bobby Flay was challenging other top toques on Food Network’s “Iron Chef America” (Sun., 9 p.m.). The celeb chef has now set his spatula on fast food by launching Bobby’s Burger Palace joints in the New York area and a book, “Bobby Flay’s Burgers, Fries and Shakes” ($26, Clarkson Potter). We chatted him up about flipping, frying and shake-making.

» EXPRESS: Have you learned anything by running burger restaurants?
» FLAY: People want burgers cooked more than I think they should. They don’t want to see pink, but I recommend burgers medium-rare.

» EXPRESS:What’s the secret to a burger?
» FLAY: People overthink hamburgers. You just have to use chop meat that has enough fat, 20 percent, season it on both sides, and turn it once.

» EXPRESS: What should I cook my burger in?
» FLAY: A cast-iron pan. You flip the patty just once. It gets a nice crust.

» EXPRESS: The book has cool flavor combos: feta and cucumber-topped Greek burgers, garlic-butter burgers. How’d you come up with them?
» FLAY: I’m inspired by experiences I’ve had. I try to focus on one place. Onions, mushroom and thyme is cool on a burger, but it doesn’t have a story. Like a Napa Valley Burger gets Meyer lemon mustard and goat cheese, and a Santa Fe Burger is topped with green chilies.

» EXPRESS: What’s the best burger cheese?
» FLAY: I like American cheese, though some chefs might not agree. It’s a perfect melting cheese! I also like Swiss and Gruyere.

» EXPRESS: What about bread?
» FLAY: Bread for burgers has got to be soft. You want the bun to become part of the burger as you are eating it.

» EXPRESS: Isn’t making fries at home tricky?
» FLAY: Without a doubt. But you can make shoestring fries easily — you just fry them once.

» EXPRESS: Any secrets to good shakes?
» FLAY: The key is a lot of ice cream. It should be slightly melted before you put it in, then pulsed for about 30 seconds.

» EXPRESS: You TV shows often involve culinary battles. Why?
» FLAY: Everyone is competitive in some way. It’s fun to be competitive with cooking because, in the end, we all get to eat good food.

Try it yourself: Make Flay’s mint-chocolate shake.

Photo courtesy Ben Fink