Mix the millet and quinoa in a large bowl. Rinse the grains several times under running water, rubbing them together with your fingers, until the water stops foaming and runs clear.
To cook the grains to the texture I think is ideal, where they won’t stick together, put 6 cups of water in a large saucepan. Add the grains, bring the water to a boil, and cook until the millet softens and the quinoa pops and forms little tails at the end, about 15 to 20 minutes.
Pour the cooked grains through a strainer, being very careful that the hot water doesn’t burn you; there may be about a cup of water remaining. Or, bring 2 cups of water to a boil in a medium saucepan.
Add the grains, lower the heat to a simmer, and cook until all the water is absorbed and the grains are tender enough to fluff with a fork, about 15 to 20 minutes. If you’ll be serving the salad cold, chill the grains in the refrigerator until you’re ready to use them.
Heat a small dry skillet over medium-low heat. Put in the almonds and toast for a few minutes, tossing or stirring frequently, until the nuts are fragrant and lightly browned. Let the almonds cool before using.
When the almonds are cool enough to handle, coarsely chop them and put them in a large bowl, along with the cherries, onions, jalapeño, lime juice, and cilantro. Add the grains and combine. Garnish with the mint.