Preheat the oven to 400°F (200°C). Line a baking sheet with parchment paper or lightly grease it.
In a bowl, toss the sliced bell peppers, sliced red onion, and cherry tomatoes with 1 tablespoon olive oil. Season with salt and pepper. Spread the vegetables on the baking sheet and roast for 20–25 minutes, or until tender and lightly caramelized.
Meanwhile, warm a large skillet over medium-high heat and add the remaining 1 tablespoon olive oil.
Add the ground turkey and ground beef to the skillet, breaking them up as they cook. Stir in the harissa paste, cumin, cinnamon, garlic, salt, and pepper. Continue cooking for about 6–8 minutes, or until browned with no pink remaining.
In a small bowl, whisk together the tahini and lemon juice. Add water a little at a time until the sauce reaches a pourable consistency. Season with a pinch of salt.
To assemble, divide the fresh spinach among four bowls or meal-prep containers. Top each portion with roasted vegetables and the harissa-spiced meat mixture.
Drizzle the tahini-lemon sauce over everything. Garnish with chopped almonds or pumpkin seeds if desired.