Preheat oven to 400°F (200°C). Melt 1 tbsp (15 mL) coconut oil in large, non-stick skillet over medium heat. Cook onions 8 min. until softened. Stir in chickpeas and 1/4 cup (60 mL) curry paste. Cook 2 min. until chickpeas are well coated. Stir in tomatoes; bring to a simmer. Reduce heat to medium-low and cook about 15 min. until sauce starts to thicken. Stir in 1/4 cup (60 mL) cilantro and lime juice. Measure out 2 1/2 cups (625 mL) chickpea mixture into a bowl and set aside. Spread remaining chickpea mixture from skillet in bottom of 8-in. (20-cm) square baking dish; set aside.
In same skillet, crumble in ground beef. Cook about 8 min. to lightly brown. Stir in remaining curry paste; cook about 1 min. Stir in reserved chickpea mixture in bowl; bring to a simmer. Spread mixture in bottom of another 8-in. (20-cm) square baking dish.
Meanwhile, cook potatoes in boiling salted water until very tender, about 20 min. Reserve 1/3 cup (75 mL) cooking liquid, then drain potatoes well. Transfer potatoes back to saucepan. Add remaining coconut oil. Mash; adding reserved cooking liquid. Divide potato mixture between the 2 baking dishes; spreading with spatula to cover chickpea filling. Sprinkle with mustard seeds.
Bake 25 min. until golden brown and bubbling. Sprinkle with remaining cilantro to serve.
Please note nutritional analysis is based on 1/8th of entire recipe, averaged from vegetarian and