Place the beef stew meat, sliced onion, minced garlic, and grated ginger in the slow cooker.

Add the coconut milk, Thai red curry paste, fish sauce, and brown sugar. Stir everything together until the curry paste is mostly dissolved.

Cover and cook on low for 6 hours.

Stir in the sliced bell peppers, then continue cooking for 1 more hour until the peppers are tender but still slightly crisp.

Turn off the heat and stir in the lime juice.

Spoon the curry over cooked rice and top with fresh cilantro before serving.