1 Make The Tomatillo Sauce. Remove The Papery Husks From The Tomatillos And Rinse Well. Cut The Tomatillos In Half And Place Them Cut-Side Down On An Aluminum Foil-Lined Roasting Pan. Broil For 5-7 Minutes Until Blackened In Spots. Let Cool Enough To Handle. Place The Tomatillos, Any Juice They Have Released, Chile Peppers, Garlic, Salt, Lime Juice And Sugar In A Blender, And Pulse Until Well Blended. If You Make Ahead, Refrigerate Until Needed. 2 Heat A Couple Tablespoons Of Olive Oil In A Large, Thick-Bottomed Pot On Medium High Heat Until Almost Smoking. Pat Dry The Cubed Chicken Parts With Paper Towels. Sprinkle Salt And Pepper Over Them. Working In Batches So As Not To Crowd The Pan, And Adding More Olive Oil When Necessary, Brown The Chicken Pieces On Two Sides. When You Place The Pieces In The Pan, Make Sure There Is Room Between Them (Otherwise They Will Steam And Not Brown), And Don'T Move Them Until They Are Browned On One Side. Then Use Tongs Or A Metal Spatula To Turn Them Over And Don'T Move Them Again Until They Are Browned On The Other Side. Do Not Cook Through, But Only Brown. Remove The Chicken Pieces From The Pan And Lower The Heat To Medium. There Should Be A Nice Layer Of Browned Bits (Fond) At The Bottom Of The Pan. 3 Add The Onions To The Pan, And A Tablespoon Or Two More Olive Oil If Needed (Likely). Add Ground Cumin And Coriander. Cook A Few Minutes, Stirring Occasionally Until Onions Are Softened And The Browned Bits From The Chicken Have Been Picked Up By The Onions And Are No Longer Sticking To The Pan. Add The Garlic And Cook For 30 Seconds More, Until Fragrant. 4 Add The Browned Chicken, The Tomatillo Sauce, Chicken Stock, And Oregano To The Pan. Stir To Combine. Bring To A Boil And Reduce To A Simmer. Cook, Partially Covered, For 20 Minutes Until Chicken Is Cooked Through. Add The Cilantro To The Stew In The Last Minute Or So Of Cooking. Serve Over White Rice, Accompanied With Sour Cream If Needed To Offset The Heat From The Chiles. The Stew Will Thicken As It Cools.