Place the rice, water and 1/2 teaspoon salt in a small saucepan and bring to a boil over medium-high heat. Reduce the heat to low, cover and simmer until the rice has absorbed all the water and is tender, 40 to 50 minutes. Turn the rice into a large bowl to cool.

Roast the corn in a dry heavy skillet over high heat until it is blackened in spots.

Purée the milk, eggs and half the roasted corn in a processor until smooth. Add the corn purée to the rice and stir to combine.

Place the flour, baking soda, remaining teaspoon salt and cumin in a small bowl and stir to combine. Add the dry ingredients to the corn mixture and stir until just moistened. Fold in the remaining roasted corn and minced onion.

Heat a heavy skillet over medium-high heat. Add 1 tablespoon each of the butter and oil. When hot, drop the pancake batter by 1/4 cup measurements into the skillet, flatten the pancakes slightly and cook until golden brown, about 2 minutes. Flip the pancakes and cook 2 minutes more.