So I'm learning to cook in cast iron, I have cornbread, pies, omelets, scrambled eggs, and fish down pretty good. Tonight I decided to try a couple burgers, in a newly seasoned Favorite smiley 8, it's had 5 rounds of crisco. The burgers fried ok, but my question is why I got the mess in the bottom of the pan. Being a newly seasoned pan I added just a bit of bacon grease I keep in the fridge, just enough to make the surface slick. Did the stickiness bits come from the bacon grease, or is it because the beef is raised by a friend and not very fatty? Also what is recommended for cleaning this up? This pic is after I used a Lodge scraper, and the edge of my metal spatula but didn't want to dig at it. Or just leave it and keep cooking? Trouble I have with that is all the time you spend cleaning and restoring a skillet it's hard to leave it looking like that, any help is appreciated.
https://imgur.com/a/E98gO
https://imgur.com/a/E98gO