It sounds heretical, particularly since the outdoor cooking season is getting started, but here goes: For a truly delicious burger, skip the grill, stay indoors and reach for a cast-iron skillet.

This advice is gleaned from interviews that I conducted with more than 100 Twin Cities chefs between 2013 and 2019 for an online column called Burger Friday, where I dissected the secrets behind burgers encountered in venues that ranged from drive-ins to food trucks to four-star kitchens.

A skillet allows the patties to baste in their own juices as they cook. That's a huge improvement over losing all-important moisture to the spatters that cause annoying grilling flare-ups.

Using the right beef is also key. Begin by selecting the lowest percentage of lean ground beef that's available, remembering that the lower the number, the higher the fat content and the juicier the burger. Stick with 85% or lower. If you have access to a butcher, ask for freshly ground chuck. It's even better if the beef can be fortified with bits of richer cuts, such as brisket or sirloin.

With as little handling as possible, form the ground beef into 3- to 4-ounce meatballs. Place the meatball into a hot cast iron pan over medium heat. Using a wide, thin spatula, smash the meatball into the pan until a thin (about ⅓ inch) patty forms. Cook, undisturbed, until the edges are crisped and browned, about 2 to 2 ½ minutes. Carefully extricate the patty from the pan, flip it and then cook for an additional minute.

OK, there's a little bit more to it than that, but not much.

The all-important bun

When selecting a bun, consider the bread-to-beef ratio. Don't allow one component to overpower the other. Toasting the bun instantly elevates the burger's appeal. Even the most generic, plastic-wrapped, eight-pack supermarket bun will blossom under the toasted treatment. Just after removing the patties from the skillet, spread room-temperature butter across the flat inside surfaces of the bun and let the skillet's heat work its magic, until the bread is lightly browned and slightly crisped.

Keep in mind

• Seasoning is key. It's best to season the top of the patty once it's in the pan and smashed. Stay old school and make a mix of sea salt and freshly ground black pepper. Or start there, then add dried rosemary, thyme, sage, marjoram, powdered onion, powdered garlic and/or other favorite aromatics. Or toast the peppercorns before grinding them.

• Two thin patties will always be an improvement over one thick patty. It's all about increased surface area. All-important flavor (and, to a lesser extent, texture) flows from the sizzled char that's created where the beef meets the pan. Two patties have twice as much surface-to-pan area as a single patty.

• Some argue for frying in a bare skillet. Others advocate for fat. Since no one ever claimed that a hamburger constituted health food, go ahead and fry the patties in butter or bacon fat. A nice trick is to slowly brown thinly sliced onions tossed with fresh thyme in lots of butter and then use the onions as a garnish. Remove the cooked onions, add a little more butter then fry the patties in the same pan.

• Consider elevating the meat's fat content by incorporating small pieces of butter into the ground beef, using the paddle attachment of a stand mixer or by mixing with your hands. Over the course of my research, some chefs followed a 1-to-10 ratio of butter to beef, and several went as over-the-top as 1-to-2 ratio.

• To facilitate a browned crust, spread mustard on the uncooked meatball just before it hits the pan.

• For cheeseburgers, the time to add the cheese is right after the patty is flipped. There are reasons why American is often the cheese of choice. It melts like a dream, it's salty and it hits all kinds of nostalgia buttons.

• For Cheddar, Swiss, pepper jack, Brie and other alternatives, the melting process will be improved if the cheese is grated and then sprinkled on top of the patty.

• Tomatoes are a delicious burger add-on, but only when they're locally grown and at their peak. For cottony out-of-season tomatoes, consider roasting or broiling to boost their pallid nature.

• Engineering is important. Placing lettuce, pickles (a must, for their cleansing acidity and crunch) or other vegetables under the patty creates a barrier that keeps the bun from becoming soggy from the patty's juices.

The right sauce

Consider making this all-purpose condiment — it's from "Shake Shack: Recipes & Stories," by Randy Garutti and Mark Rosati — because it's one of many reasons why burgers at the quick-service chain are so popular.

It's easy, and it keeps for up to a week in the refrigerator. In a small bowl, combine ½ cup mayonnaise, 1 tablespoon Dijon mustard, ¾ teaspoon ketchup, ¼ teaspoon pickling brine from kosher pickles (the "juice" in the pickle jar) and a pinch of cayenne pepper.

Taking it outside

For those who view burgers on the grill as an essential summer ritual — and isn't that just about every burger lover? — follow these expert instructions, from "The Big Book of Outdoor Cooking & Entertaining," by Cheryl and Bill Jamison.

Fire up the grill for a two-level fire capacity of cooking first on high heat (you'll be able to hold your hand a few inches over the grilling grate for 1 to 2 seconds before the heat of the fire forces you to pull away) and then on medium heat (4 to 5 seconds with the hand test).

Season ground chuck with salt and pepper. Gently form the mixture into patties ½- to ¾-inch thick, making the patties completely flat or even slightly concave. The patties should hold together firmly, but avoid handling them any longer than necessary.

Grill the burgers uncovered over high heat for 1 ½ minutes per side. Move the burgers to medium heat and rotate a half-turn for crisscross grill marks. Don't under any circumstances mash the burgers with the spatula. Cook for 3 ½ to 4 minutes more per side for medium doneness, until crusty and richly brown with a bare hint of pink at the center. Eat hot from the grill.

Rick Nelson • @RickNelsonStrib