Heat a large skillet over medium high heat and some oil and butter while working in batches and lightly sear the meat on all sides (I find it saves time to use bigger chunks and allow them to rest then cut into bite-sized pieces, but you can do that in reverse).

Once complete with all the meat, transfer to plate (if desired lightly salt the meat while resting).

If desired, you can remove some of the fat that has gathered from the meat, then add carrots and onion and cook until soft, then garlic for 1 minute. Reduce the heat to medium if needed.

Cook tomato paste for 2 minutes, then add beer and deglaze the pan for about 3 minutes (it should be thick).

Add seared lamb and rosemary sprigs, Worcestershire, salt and pepper. Mix well and bring to a boil, then reduce to low and cook for an hour, covered (keep a light boil going the whole hour).

Remove the rosemary sprigs and add potatoes to the Dutch oven and cook for an additional 45-60 minutes, uncovered or until the potatoes are almost fork tender.

Once the potatoes are cooked, taste and add any additional season, or water if desired at this time. Then combine flour and ½ cup water to a spouted measuring cup and whisk. Pour this into the pot and bring to a rolling boil (not too aggressive) for about 15-20 minutes or until it has thickened slightly.

When ready to serve add in the peas and stir to combine (they will warm up and soften quickly).