Season chicken generously with salt and pepper. Heat Olive Oil in medium saucepan. Add chicken, skin side down and cook, without moving, until well browned. Flip chicken and cook for another 2 minutes. Trasfer to large plate and immediately add tomatillos, tomatoes, and garlic to pot, flipping occasionally, until blistered and browned in spots, about 5 minutes.
Add onion and cook, stirring, until softened, about 2 minutes. Add oregano, bay leaves, and cook, stirring, until aromatic. Add balsamic and stock. Return chicken to pot, bring to boil, then reduce to bare simmer. Cover pot and cook until chicken tender and done. Transfer chicken to bowl and set aside. Continue cooking the sauce at a hard simmer, stirring, until reduced to about half its original volume.
Add chipotle chilies and adobo, remove and discard bay leaf. Blend the sauce using an immersion blender. Sauce should be relatively smooth, with a few small chunks. When chicken is cook, discard skin and bones and finely shred the meat. Return to the sauce. Add fish sauce and stir to combine.
Bring to simmer and cook. stirring, until sauce thickens and coats chicken. Season to taste with salt and pepper. Chicken tinga can be served in tacos; stuffed enchiladas; on top of nachos, tostadas, and sopes.
Place potatoes, 1 tablespoon salt, 1 tables vinegar, and 3 cups water in medium pot. Bring to boil over high heat. Cook potatoes until tender. Drain, reserving 1/2 cup of cooking liquid. Immediately toss potato pieces with 1/2 tablespoon vinegar and set aside.
Combine reserved cooking liquid with remaining vinegar, mustard, relish, sugar, and minced shallot in a large bowl. Add 5 to 6 pieces of cooked potato. Mash until smooth. Whisking constantly, add Olive Oil, capers, celery, sliced shallot, parsley, and potatoes. Season to taste with salt and pepper.
Thinking about gathering your friends and family for some grilling, sipping, and celebrating this Summer Season? We have LOTS of SIMPLE ideas, and here is another DIY healthy, super tasty salsa to impress your friends.