Pat roast all over with paper towel to dry. No need to remove fat. Generously season all sides with salt and pepper (I use 2 teaspoons salt and 1-1/2 teaspoons pepper). Spray a 6-quart slow cooker with cooking spray.
While searing the roast (see next step), add everything to the prepared slow cooker: Herbs de Provence, cumin, dried oregano, dried parsley, beef bouillon powder, tomato paste, crushed tomatoes, Worcestershire sauce, and sun-dried tomatoes (use a fork to pull them from jar and measure). Stir together in the slow cooker and press into an even layer.
Warm 2 tablespoons of the oil surrounding the sun-dried tomatoes (or olive oil) in a large Dutch oven (or oven-safe heavy-bottomed pot) over medium-high heat. Once you can feel heat if holding your hand 6 inches above the pot, place seasoned chuck roast in pan. Brown beef about 4–5 minutes per side. (To get a good sear, let beef cook without being turned; it will release easily once seared).
Once nicely seared with a good crust, remove and place in slow cooker on top of tomato and seasoning mixture (if there is a fat cap, place cap facing up so fat can drip down and flavor the roast). Add in bay leaf.
Allow Dutch oven or pot to cool 5 minutes after removing beef, then return it to medium-high heat and add another 2 tablespoons of oil surrounding the tomatoes (or olive oil). Add diced onion and minced garlic. Stir and cook until tender, scraping up any bits left from the meat, about 5 minutes. Pour this mixture over roast in slow cooker. Gently spoon the cooking liquid over the beef.
Cover, and cook on low for 7–9 hours (8 hours is perfect in my slow cooker). Once beef is cooked and shreds easily, remove and scrape off any fat cap. Shred beef with two forks and return it to the slow cooker, gently stirring it into the sauce. Set the slow cooker to warm and season beef with salt and pepper, then with lemon juice if desired (1–3 tablespoons to taste).
I like to prepare this sauce when starting the beef so it has a chance to get more flavorful before serving! From tzatziki sauce ingredients, grate cucumber with the large holes. Line a small bowl with paper towels (or a clean kitchen towel) and place grated cucumber on top. Squeeze out as much moisture as you can from the cucumber (to keep the sauce from being watery), then add to a medium bowl. Zest and juice lemon to get 1/2 teaspoon zest and 1 tablespoon juice. Add in Greek yogurt, minced garlic, red wine vinegar, lemon zest, lemon juice, olive oil, and salt and pepper to taste (I add 1/4 teaspoon salt and 1/8 teaspoon pepper). Cover bowl and place in fridge until ready to serve.
From salad ingredients, in a medium bowl, combine cucumbers, tomatoes, parsley, and red onion. In a small bowl, stir together lemon juice, oil, paprika, and salt and pepper to taste (I add 1/4 teaspoon salt and 1/8 teaspoon pepper). Whisk with a fork. Drizzle dressing over vegetables and stir to coat.
Spray both sides of the pita bread with cooking spray and “grill” the bread on the stovetop on medium hear over an open flame until slightly charred, about 10–15 seconds per side (flip with tongs). Immediately fold in half after charring and cover with a clean towel until ready to serve. Alternatively, warm (covered with a damp paper towel) in the microwave.
Set everything out: pita, sauce, and veggies. Top pita bread with meat, veggies, and a drizzle of tzatziki sauce. Enjoy immediately, garnished with additional parsley if desired. Optionally serve with lemon wedges, and drizzle lemon on before enjoying!
Notes
Note 1: These are the sun-dried tomatoes used in this recipe. They’re sliced (julienne cut) and packed with herbs and olive oil. They add a lot of flavor to the beef, and you don’t need to chop them. To infuse the meat with even more flavor, use the oil surrounding these sun-dried tomatoes. If you aren’t able to find oil-packed sun-dried tomatoes, use regular olive oil instead.Note 2: There is a higher yield of shredded beef to sauce and veggies. If you plan to use all the beef for gyros, I’d recommend doubling the sauce and veggies. Alternatively, Use leftover beef in these baked sweet potatoes or this Beef Ragu. You can also freeze leftover beef for gyros in the future!Storage: Cool and store beef in an airtight container in the fridge for up to 3 days or freeze for up to 3 months. Refrigerate tzatziki in a sealed container for up to 5 days. The salad is best fresh but can be refrigerated for 1–2 days. Keep pita bred at room temperature for 1–2 days or freeze.