In a small bowl, combine curry powder, cumin, salt, and pepper. Trim fat from meat. Cut meat into 1-inch pieces; place in bowl. Sprinkle spice mixture over meat pieces; toss to coat. Place meat in a 4-1/2- to 6-quart slow cooker. Add undrained tomatoes, celeriac, cauliflower, onion, and apple.
Cover and cook on low-heat setting for 9 to 10 hours or on high-heat setting for 4-1/2 to 5 hours.
Turn off cooker. Stir in coconut milk and peas. Cover and let stand for 5 to 10 minutes or until heated through.
Meanwhile, in a small bowl, combine yogurt, cucumber, and lime juice. Top each serving with yogurt mixture. Makes 8 servings.