Step 1

In a large Dutch oven, heat vegetable oil over medium-high heat. Season lamb with salt and pepper. Working in batches, cook lamb in a single layer until well browned on all sides, about 8 minutes per batch.

Step 2

Return all of the lamb to Dutch oven, add garlic and onions, and cook until onions are soft, 6 minutes. Add flour and cook until it is well browned, 2 minutes.

Step 3

Add wine, and cook for 2 to 3 minutes, scraping browned bits from the bottom and sides of pan. Add stock, tomatoes, rosemary, thyme, and bay leaf. Bring to a boil, then reduce heat to low; cover and cook until meat is tender, 1 1/2 to 2 hours.

Step 4

Remove meat, place in a large bowl, and set aside. Reduce sauce over high heat until thickened, about 10 minutes. Adjust seasonings. Skim off any fat. Strain sauce over meat, discarding solids; return meat and sauce to Dutch oven. (The navarin can be made ahead up to this point. Cover and refrigerate for up to 2 days. Reheat and continue as directed.)

Step 5

Bring a small saucepan of water to a boil, and add pearl onions. Boil 2 minutes, then drain. When onions are cool enough to handle, peel and set aside. Peel baby carrots; trim tops to 1/4 inch. Repeat with baby turnips. If using large carrots and turnips, peel and cut into 1/2-inch pieces. Add onions, turnips, and carrots to Dutch oven and simmer, covered, for 30 minutes. Add peas and simmer 10 minutes more, or until vegetables are tender.

Step 6

Blanch beans until bright green and still crisp, about 5 minutes, then drain. Serve and scatter beans atop each serving.