Cook the rice in your usual way (on the stove top or in a rice cooker). Replace one can's worth of water with the coconut milk. Then add in an extra quarter cup of water.
Roughly puree the mango, jalapeno, garlic, red onion, cilantro, and kosher salt in a mini food processor. You will wait to retain some texture so blend for 10 seconds.
Warm your serving bowls or plates. Heat the oil in a large skillet over medium-high heat. When it is shimmering, add the plantains in a single layer. Fry, until brown on one side, about 3 minutes. Flip and cook on the other side until browned and tender, about 2 minutes. Sprinkle with kosher salt.
To serve, you may either divide the rice among four bowls and top with plantains, beans, avocado, mango, cilantro, and sauge. Or serve all of the ingredients separately and let diners make their own. Pass the lime quarters to squeeze over the finished plate as desired.