Add 200g rice to a pot with roughly 400ml water. Bring to a boil, then reduce heat to low, cover, and simmer for 15-18 minutes until water is absorbed.
While rice cooks, drain the 2 cans of white beans. Heat a pan over medium heat, add the beans with a lid, and warm for 5-7 minutes. Season with salt and pepper and set aside.
Prepare the mango salsa: Finely chop the onion and cut the mango into small pieces. Mix together in a bowl with 2 tablespoons of lime juice. Season with salt and pepper to taste.
Wash the salmon fillets and pat dry. Season both sides with salt and pepper.
Heat a pan over medium-high heat. Add the salmon fillets skin-side up and cook for 6-8 minutes. Flip and cook for another 4-6 minutes until the internal temperature reaches 63°C (145°F).
Fold the warmed beans into the cooked rice.
Serve the salmon alongside the rice and beans, topped with the mango salsa.