1. Combine vital wheat gluten with the spices, including salt, and briefly mix in a food processor.
2. Add pureed beetroot, one tablespoon of mustard, tahini, and maple syrup, and process until a dough forms. Knead the dough for 3-4 minutes until it firms and is no longer sticky. If necessary, add more vital wheat gluten while kneading.
3. Shape the dough into a cylindrical log. Heat a large skillet with a little oil, brush the roast with the remaining mustard, and sear on all sides. Add white wine, broth, onion, carrots, garlic cloves, rosemary, and thyme, and simmer covered on low heat for 90 minutes. As needed, add more broth, and flip the roast occasionally.
4. Once cooked, heat a large skillet with a little oil and sear the roast on all sides for 3 minutes to develop a crust. Slice the roast thinly and serve at once.
5. Puree the vegetables with the leftover broth and use as gravy. Adjust consistency with a splash of water if necessary.
6. For a more pronounced meaty texture, refrigerate the roast overnight, then reheat briefly in the oven the next day.