For the applesauce: Put the apples, lemon juice, brown sugar, sugar, cinnamon and salt in a heavy-bottomed saucepan with a lid. Bring to a boil, then cover, turn to heat to low and simmer, stirring occasionally, until the apples are completely soft, 20 to 30 minutes. Taste, and add more sugar if desired.
Off the heat, mash the apples well with a potato masher or a fork. Allow to cool before serving in the parfaits.
For the crispy quinoa: Preheat the oven to 325 degrees F. Line a baking sheet with parchment. Toss the quinoa, coconut oil and honey in a bowl and spread in an even layer on the prepared baking sheet. Bake until lightly golden brown, about 20 minutes. Remove to a baking rack to cool.
For the parfaits: Mix together the yogurt, vanilla bean seeds and vanilla extract in a bowl. Spoon some of the yogurt mixture into four parfait glasses. Scatter some quinoa on top, then spoon in a thick layer of applesauce. Sprinkle with more quinoa, add another thick layer of yogurt, and sprinkle again with quinoa. Add a dollop each of applesauce and yogurt, and a final sprinkling of quinoa. Garnish with fresh mint sprigs if desired.