In a cast-iron skillet over medium heat, add oil. Add onion, garlic, ginger and salt and saute for 2 minutes. Stir in red curry paste and saute for another minute.
Add lentils and toast until combined. Whisk in coconut milk and bring to a simmer. Let cook for 15 minutes until lentils are al dente.
Add cauliflower and continue cooking until both lentils and cauliflower are tender. Add spinach and stir until wilted.
In a bowl, add rice. Ladle lentils and curry over rice. Top with cilantro and lime wedges.