Wash hands with soap and water.
Gently rub zucchini and yellow squash under cold running water and cut into large bite-size pieces.
Scrub the onion and fresh garlic with a clean vegetable brush under running water and cut into large bite-size pieces.
In a medium bowl, mix together the all-purpose flour, ½ teaspoon of salt and ¼ teaspoon of black pepper. Add the stew meat and toss to coat the meat with the flour mixture. Wash the bowl and utensils with soap and water. Wash hands with soap and water after handling raw flour.
In a large skillet over medium heat, add the olive oil and stew meat. Brown the meat on all sides. Wash hands with soap and water after handling raw meat.
Once the meat is browned, add it to the slow cooker.
Mix in 1 teaspoon salt, ½ teaspoon black pepper, rosemary, basil, and garlic powder.
Stir in the onion, fresh garlic cloves, and diced tomatoes.
Add the cinnamon sticks, one on each side of the slow cooker near the handles.
Cover and cook on low for 6-7 hours or on high for 2-3 hours, then add the zucchini and yellow squash. Mix to combine and cook for 1 more hour, until the meat is tender and reaches 145°F on a food thermometer.
Remove the cinnamon sticks and serve over couscous or brown rice.