Season chuck roast generously on both sides with Kosher salt and freshly ground black pepper. In a large (10-inch) heavy bottomed skillet, heat olive oil over high heat until it's hot, shimmers and just begins to smoke. Add chuck roast. Brown the roast, undisturbed, for about seven minutes. Use a pair of tongs and flip. Cook for an additional seven minutes. Using your tongs, brown the sides of the roast for about two minutes per side. You need to hold the roast as you do this. Transfer roast to the slow cooker.

Reduce heat to medium-low. Add the onions to the hot pan. Cook until they just start to turn brown, about four minutes. Stir the onions occasionally. Transfer onions to the slow cooker. Repeat with carrots. Cook for four minutes, stirring occasionally. Transfer carrots to the slow cooker.

Add garlic cloves to the slow cooker. Evenly spread the tomatoes over the top of the slow cooker. Add beef stock. Cover and cook on low for eight hours.

After eight hours, remove chuck roast from the slow cooker. Cut into thick pieces. Place on a platter and cover with aluminum foil. Strain out the onions, carrots, and tomatoes. Ladle the cooking liquid into a two-cup measuring cup. Skim the fat off the top. Pour cooking liquid over the slices of roast. Serve.