When Tyler Florence was creating hamburgers for his new restaurant, his goal was simple – a burger that stays moist no matter how well-done it is cooked.

The solution was all a matter of numbers – one month of experimenting with the percentage of fat and the number of cuts of meat.

"Most people do an 80-20 lean-to-fat ratio," Florence, whose Wayfare Tavern opened recently in San Francisco, said in a telephone interview. "We go 75-to-25 ratio, so it’s a little fattier. So even if you like it well done, it’s still nice and moist."

For the cuts of meat, Florence settled on four of them – prime rib, brisket, skirt steak and filet. And after they are ground (at another facility), it’s mostly a hands-off procedure.

"When it comes in, no one is really allowed to touch it except to take it out of the package and weigh it out," said Florence, host of Food Network’s The Great Food Truck Race. "It gets touched once before it goes on the grill. It loses that fluffiness once you work it too much. It starts to become chewy really quickly."

Florence was equally exacting when it came toppings. "You can’t just put stuff on top of the burger for the sake of it," he said. "To me, it’s got to be very purposeful stuff. You have to really think it through so it’s a complementary flavor and not a distraction from the burger."

Wayfare Tavern Burger

Serves 8

1/2 pound ground prime rib

1 pound ground brisket

1 pound ground skirt steak

1/2 pound ground filet

8 hamburger buns (recipe below)

Kosher salt and pepper

1 large red onion, sliced into 1/4-inch rings

1 cup lemon aioli (recipe below)

1/2 pound brie (Florence favors Cowgirl Creamery Triple Cream Brie), cut into thin slices

In a large bowl, mix the prime rib, brisket, skirt steak and filet together until well blended, but not overworked. Divide the meat into 8 portions and shape into patties. Season with salt and pepper.

Heat the oven to 400 F. Line a baking sheet with parchment paper. Arrange the onion slices in a single layer on the prepared pan. Roast the onion slices for 10 to 12 minutes, or until tender. Set aside.

Heat the grill on high. Grill the burgers to desired temperature, about 4 minutes on each side for medium-rare. Top the bottom half of each roll with a burger, some of the red onions, aioli and brie.

Wayfare Tavern

Burger Buns

Makes 8 buns

1 cup warm water

1⁄4 cup warm whole milk

1⁄4-ounce package active dry yeast

2 1⁄2 tablespoons sugar

2 eggs

3 cups bread flour

1⁄3 cup all-purpose flour

11⁄2 teaspoons salt

21⁄2 tablespoons unsalted cold butter, cut into 1⁄4-inch pieces

In a medium bowl, combine the water, milk, yeast and sugar until well blended. Let stand until foamy, about 5 minutes. In a small bowl, lightly beat one of the eggs. In a large bowl, whisk together the bread flour, all-purpose flour and salt.

Gradually add the butter, beaten egg, and yeast mixture, mixing with a pastry scraper or clean hands until a sticky dough forms. Knead this mixture on a clean, well-floured surface for 6 to 8 minutes, or until the dough is smooth.

Place the dough in a large bowl, cover with a clean towel and let stand for 1 to 1 1/2 hours, or until the dough has doubled in size. Divide the dough into 8 portions. Roll each portion into a ball and place on a parchment-lined baking sheet about 2 inches apart. Cover the pan loosely with plastic wrap and let stand for another hour, or until the rolls have risen slightly.

When ready to bake, place a large shallow pan of water on the floor of the oven and heat the oven to 400 F. In a small bowl, lightly beat the remaining egg with 1 tablespoon of water. Brush the mixture over the top of each roll. Bake the rolls for 15 to 20 minutes, or until golden. Transfer the rolls to a rack and let cool completely.

Wayfare Tavern Lemon Aioli

Makes 1 cup

1 egg yolk

Juice of 1⁄2 lemon

2⁄3 cup grape seed oil

Salt and ground black pepper

In a food processor, combine the yolk and lemon juice. Pulse until just combined. With the processor running, gradually pour in the grape seed oil. Process until the mixture is creamy and emulsified. Season with salt and pepper, then cover and chill until ready to serve.

When Eric Ripert set out to make the perfect burger, he found his inspiration in an unlikely place.

"It may sound crazy coming from a French chef, but the inspiration behind this burger is actually McDonald’s and Burger King," said Ripert, the man behind New York’s award-winning Le Bernardin restaurant and Westend Bistro in Washington.

For Ripert, a great burger must be perfectly proportioned, a trait he thinks the fast food giants have aced.

"All the elements are carefully controlled," he said via e-mail. "The way they cut the pickles, the way they cut the tomatoes, the way they slice the salad, and the size, obviously make those burgers perfect."

Except the meat, that is.

"So what we did was we looked at their burgers carefully and studied the proportions, and then of course did the same thing, but with great meat," he said. "We’re using sirloin mostly, but it’s the fat content and ratio of fat to meat that is very important."

And don’t forget a great bun. Ripert favored a fresh challah bun for his perfect burger.

Westend Bistro Burger
Serves 4

28 ounces ground sirloin (85 percent lean)

Kosher salt and ground black pepper, to taste

4 challah buns

2 tablespoons butter, softened

4 slices cheddar cheese

4 pickle slices

Ketchup and Dijon mustard, to taste

1 beefsteak tomato, sliced into four 1/4-inch-thick slices

1 yellow onion, thinly sliced, soaked in ice water until crisp

4 leaves crisp romaine lettuce, shredded

Heat a grill to medium. Lightly oil the grates. Form the beef into four 7-ounce patties. Season with salt and pepper. Grill the burgers, flipping once, to desired temperature . Cover and set aside.

Brush the insides of the buns with the softened butter and grill until golden. Set aside.

Heat the broiler. Top each burger with a slice of the cheese, then place under the broiler until just melted. Place each burger on the bottom half of a roll.

Top with a pickle, then ketchup and mustard, then the tomato, onion and lettuce. Finish with the top of the bun.