Preheat oven to 425°F (220°C). To wilt spinach, microwave spinach on HIGH in microwaveable bowl with 1 tbsp (15 mL) water for 1 min. (or bring 1/2-in./1-cm water to simmer in saucepan and stir in spinach to wilt). When cool enough to handle, squeeze spinach dry. Meanwhile, drain artichokes, reserving 2 tbsp (30 mL) liquid from jar. Finely chop artichokes. Mix spinach, artichokes and cheese. Set aside.
Without slicing all the way through, cut into roast horizontally and open up like a book into one bigger piece. Pound to 3/4-in. (2-cm) thickness. Mound artichoke mixture in a "strip" down centre of roast. Roll meat around filling into cylindrical shape and tie with kitchen twine. Season with salt.
Heat 2 tbsp (30 mL) oil in large oven-proof skillet over high heat. Sear roast on all sides, about 6 min. (reserve skillet to cook lentils later). Transfer roast to baking dish or roasting pan. Roast 30 min.
Meanwhile, add remaining oil, reserved artichoke liquid, lentils, tomatoes, and garlic to skillet. Bring to boil. Remove from heat. Add mixture to baking dish holding roast in oven. Cook another 15 to 20 min., until sauce is bubbling and meat thermometer inserted into thickest part of meat registers 160°F (71°C). Stir dill into lentil mixture. Remove roast to cutting board. Let rest 5 to 10 min. Thinly slice and serve with lentil mixture.