Slow Cooker Pepper Steak

3 lb. sirloin steak, cut into strips
2 Tbsp. vegetable oil
1 heaping Tbsp. minced garlic
1 onion, chopped
1/2 c. reduced-sodium soy sauce
1 tsp. salt
1/2 tsp. black pepper
1/2 tsp. ground ginger
2 tsp. sugar
3 green bell peppers, cored, seeded and cut into strips
1 Tbsp. corn starch
1/4 c. cold water
white rice

Heat oil in large skillet over medium-low heat. Brown steak on both sides. Sprinkle garlic over steak while it cooks. Transfer steak and pan juices to slow cooker. Add onion, soy sauce, salt, black pepper, ginger, and sugar. Stir. Cover and cook on LOW 6 to 8 hours until meat is tender (up to 10 hours). In final hour of cooking, add peppers. Mix corn starch with water and add to thicken sauce.