Preheat your oven to 425°F (220°C). Press the tofu for at least 15 minutes to remove as much water as possible; this is key for a firm, meaty texture. Cut the pressed tofu into 1-inch cubes. In a small bowl, toss the tofu with the zest of half the lemon, 1 tablespoon of lemon juice, and 1 tablespoon of olive oil. Set aside to marinate.
Separate the Swiss chard stems from the leaves. Chop the stems into 1-inch pieces and roughly chop the leaves, keeping them separate for later.
On a large, rimmed baking sheet, combine the chard stems, red onion wedges, red bell pepper pieces, and sliced garlic. Drizzle with the remaining 2 tablespoons of extra virgin olive oil and a few grinds of black pepper. Toss to coat and arrange in an even layer. Roast for 15 minutes until the vegetables begin to soften and char at the edges.
While the vegetables roast, prepare the sauce. In a medium mixing bowl, whisk together the harissa paste, tomato paste, the remaining lemon juice and zest, finely chopped dates, smoked paprika, and fresh oregano to form a smooth, emulsified paste.
Add the rinsed chickpeas and cooked farro to the harissa mixture, stirring until everything is thoroughly coated.
Remove the baking sheet from the oven. Scatter the chopped chard leaves over the hot vegetables, then pour the chickpea-farro mixture evenly over the top.
Gently nestle the marinated tofu cubes and the feta blocks into the chickpea mixture on the sheet pan. Use a spoon to scoop a little of the harissa sauce over the tops of the feta and tofu.
Return the pan to the oven and bake for an additional 15-20 minutes, until the chard has wilted, the chickpeas are hot, and the feta is soft and creamy.
Remove from the oven and let rest for a moment. Garnish generously with fresh parsley and a sprinkle of Aleppo pepper. Serve hot directly from the pan.