What makes a pancake fluffy

How to make thick and fluffy pancakes

Separating the eggs and whipping the egg whites into the dough before folding it might help with this. At home it is not a problem, but if it is very busy that you had them then they probably won't as it will have to be done in batches.

Adding some baking soda on top of the baking soda can also help, but only if you are using buttermilk. If you use regular milk, the baking soda will create a soapy taste. In the case of buttermilk and baking soda, the primary sourdough would come from the baking soda, and then the acidity of the buttermilk would provide the reaction for the soda to give that extra "kick". If you are using baking soda, you must use the batter right away or these bubbles will rise to the surface and burst, releasing their CO2 into the air. Same goes for adding seltzer water ... just before cooking the pancakes.

As for replacing milk with seltzer water ... this will add bubbles to the dough, but less fat in the dough (assuming you are using whole milk) will increase gluten development. If you're using low-fat or fat-free buttermilk or regular milk, it might not make that much of a difference. The benefit of buttermilk (besides the taste) is the acidity it provides. Sour doughs do not allow gluten to develop as easily and therefore produce a more tender texture.

Mixing over pancake batter is a major problem for most people. Make a well in the center of the dry ingredients, add the liquid ingredients that have already been beaten up, then carefully fold them until they combine so that there aren't any larger pockets of dry ingredients, but the batter should pop up by no means be smooth. Mixing to a smooth consistency creates gluten and creates chewy pancakes. A few lumps are fine as they hydrate when you sit.

If you're not using baking soda and seltzer water, you can improve sensitivity by letting your pancake batter sit after 30-60 minutes of mixing. This is the idea behind pastry crust cooling. Not only does it allow gluten to relax, but most importantly, it allows the flour's starch granule to absorb moisture, hydrate, and expand (bloom). This could probably be part of what contributed to the pancakes you enjoyed in the restaurant. If it's a very busy place, they most likely produce their pancake batter in bulk a day in advance for next day service. This extended rest time would allow for maximum hydration of the starch, creating a thicker dough. The thicker the dough, the less spread you have on the grill. Obviously, this has limitations if you wake up with an appetite for pancakes!