Preheat oven to 400 F (200 C). Add sweet potato to large rimmed baking sheet and toss with olive oil, chili powder or cumin, and salt. Spread in an even layer and roast for 20 to 30 minutes, until tender and beginning to brown. Add to large mixing bowl.
For dressing, whisk all dressing ingredients until fully combined.
To cook sprouted quinoa, bring quinoa and water to a boil, reduce to a simmer, cover, and cook for 15 minutes. Turn off heat and let stand for 5 minutes. If using sprouted grain mixture, cook according to package directions. Fluff with fork and transfer to same bowl as sweet potatoes. Mix in beans or chickpeas and half of dressing.
If serving immediately, add greens and cucumbers, tossing to combine, adding remaining dressing or to taste. If making ahead for lunch, keep quinoa mixture separate from greens and cucumber, and combine right before serving.