Hmmm…so it’s only the lamb that’s bitter? This is a jab in the dark since I’m really not sure. I suppose the chocolate could factor in, but I’ve had beef dishes where chocolate was used for flavor depth without any bitter results. Have you used this particular Merlot before for marinating? Sometimes sweet or fat can help with bitter. You might try just adding a touch of sugar or ketchup, such as starting with a teaspoon and keep tasting. Or, if you don’t mind thickening the sauce a bit, try mixing equal parts soft butter and flour (beurre manié) and stirring it in (2-3 tsp. each). Otherwise, just add the butter…no flour. Hopefully someone here can be more specific.

I've never had the bitterness issue with lamb. I always use a heavy beer or Porte on my lamb. i've never used wine. I read with interest the suggested solutions and glad to hear what worked for you.

Don't thinnk the bitter was the meat.....did anotherf person also taste it and say bitter? Thinking maybe your "taster" was off a bit. I sure have had that happen....something I ate before or brushed my teeth with or drank made something taste different. and I messed with it and allw as good...shrug!

Yes, we both thought it was bitter last night. It was a dry bitter flavor. We tasted the different elements together and separately and in various orders determining where the bitter flavor was; we were initially wondering if I'd used too dark of a chocolate, as really dark chocolate has a dry, bitter flavorto it, but the chocolate wasn't very dark/bitter on its own (we ate the end of the bar straight), and it hadn't been bitter when I tasted for seasoning. We then determined it wasn't present when tasting the broth by itself but was when tasting a bite with meat, and managed to isolate the source of the bitter to the meat, which obviously I hadn't tasted prior to the finished product (being raw/undercooked meat and all). We confirmed this evening when we went to amend it that the bitter was from the meat and not the chocolate broth (one of us started with the broth then tried the meat, the other tried the meat first then the broth).

I'm wondering if it didn't come from the onion in the marinade. I think some onion/wine combos can make the meat bitter. Next time I'd replace the onion with garlic and add the onions later. And I'd simmer for 2 hours to ensure all the alcohol had cooked off.

Islay, that’s interesting. I was talking to DH about this and he suggested the onion being part of the issue. Never thought of that but who knows. Kind of a mystery!