Bring quinoa, water, and salt to a boil in a small pot. Cover and reduce the heat to a simmer. Cook for about 15 minutes, until the quinoa is tender with just a little bite to it. Don't overcook or you'll lose the texture. Remove from heat, and fluff with a fork. Set aside to cool.
Place the couscous and salt in a large bowl. Add the boiling water. Cover with a plate and let stand for 10 minutes. Remove the plate, and fluff with a fork. Add the quinoa to the couscous, and gently mix to combine. The grains should be separate and not mushy.
Mix in the chickpeas, tomatoes, cucumber, olives, artichoke, hearts of palm, parsley, almonds, and capers. Drizzle in the oil and lemon juice over everything and toss together.
To make the tahini sauce, stir everything together in a small bowl. Taste and adjust the flavors, if desired.
Serve with tahini drizzled on top.