I sauteed onions and the browned the ground beef, then lightly fried (but didn't burn) a paste made from chipotles in adobo, dried (soaked) anchos, garlic, cumin, and mexican oregano. Added the meat and onion back in with a tsp of unsweetened cocoa powder, and added water to thin.
Tasted it while it was coming up to a simmer, and there is a pronounced bitter note. Any idea what caused this and how I can fix it? I went ahead and started simmering, hoping it would mellow out a bit, but now I'm nervous!