Press the tofu for 15 minutes to remove excess moisture, then pat dry and cut into 1–2 inch cubes.
In a bowl, toss the tofu with 1 1/2 tablespoons olive oil, arrowroot starch, garlic powder, ground coriander, ground chillies (or chili flakes), salt, pepper, and 1/2 tablespoon tamari until evenly coated.
Heat a large nonstick skillet over medium heat. Add 1 tablespoon olive oil and swirl to coat the pan.
Add the tofu in a single layer and cook, stirring occasionally, until browned on all sides, about 8–12 minutes. Transfer browned tofu to a plate and set aside.
Return the skillet to medium heat, add the remaining olive oil, then sauté the diced onion until translucent and very soft, about 6–7 minutes; reduce heat if it browns too quickly.
Add the minced ginger and garlic and cook for 1 minute until fragrant.
Stir in the orange marmalade, 1/4 cup vegetable stock, and remaining 1 tablespoon tamari, scraping up any browned bits; season with salt and pepper and bring to a boil.
Reduce heat and simmer the sauce until slightly thickened, about 6–8 minutes, adding extra vegetable stock by the tablespoon if it reduces too quickly.
Stir in the lemon juice, taste and adjust seasoning, then return the tofu to the skillet and toss gently to coat in the glaze.
Serve garnished with chopped chives and toasted sliced almonds.
