Peel and cut the sweet potatoes into small cubes. Slice the scallions and roughly chop the spinach, separating the stems from the leaves where possible.
Roast the sweet potatoes at 400°F (200°C) for 20 to 25 minutes with a little olive oil until tender and lightly golden. You can also pan-fry them over medium heat until soft and browned on the edges.
Cook the quinoa according to the package instructions, usually with twice the volume of water. Simmer until the liquid is absorbed and the quinoa is tender with the little tendrils visible.
Warm the remaining olive oil in a skillet. Add the scallions and spinach stems and cook for 1 to 2 minutes until softened. Add the spinach leaves and cook just until wilted.
Briefly warm the steak if serving hot, then slice it thinly.
Divide the quinoa between two bowls. Top with spinach, sliced steak, sweet potatoes, and raisins.
Whisk together the lemon juice, tahini, olive oil, and honey until smooth. Drizzle over the bowls and serve.
This Steak Quinoa Bowl can be enjoyed warm or cold.