Pulse fennel seeds, rosemary, and red pepper flakes in a spice grinder, food processor, or blender to coarsely grind spices. In a small bowl, combine spice mixture with thyme, 1 ½ tsp. garlic powder, 1 tsp. salt, and 1 tsp. pepper.
In a large bowl, coat steak cubes with olive oil. Then add the spice mixture to the bowl and toss until the steak cubes are well coated.
Clean mushrooms with a damp paper towel and cut stems even with the bell. In a large mixing bowl, spray mushrooms with cooking spray, stir, and spray again. Season mushrooms with ½ tsp. garlic, ¼ tsp. salt, and ¼ tsp. pepper.
Place steak bites and mushrooms in an air fryer, being sure not to crowd. Cook for 8 minutes at 400°F turning halfway through cooking time. Remove steak bites and mushrooms from air fryer and tent with foil, allowing steak to rest for 2-3 minutes.
If working with 5-7 qt. air fryer, cook in batches, covering cooked steak with foil to rest and keep warm as you cook more batches.
Nutrition information per serving: 200 Calories; 69.3 Calories from fat; 7.8 g Total Fat (2.4 g Saturated Fat; 3.8 g Monounsaturated Fat); 69.1 mg Cholesterol; 552.3 mg Sodium; 4.3 g Total Carbohydrate; 1.4 g Dietary Fiber; 27.6 g Protein; 2.3 mg Iron; 623.6 mg Potassium; 0.1 mg Thiamin; 0.2 mg Riboflavin; 14.0 mg Niacin (NE); 0.7 mg Vitamin B6; 1.5 mcg Vitamin B12; 5.2 mg Zinc; 43.9 mcg Selenium; 114.5 mg Choline.
This recipe is an excellent source of Protein, Niacin (NE), Vitamin B6, Vitamin B12, Selenium, Zinc and Choline. It is a good source of Thiamin, Riboflavin, Iron, and Potassium.