Heat olive oil in a large pan over medium heat and cook diced onion for 4-5 minutes until soft and translucent.
Stir in minced garlic and cook for 1 minute until fragrant, then add rehydrated soya mince and combine well.
Mix in English mustard, vegan Worcestershire sauce, tomato puree, dried sage, and dried thyme.
Pour in vegetable stock and simmer for 5-6 minutes until most liquid is absorbed, then stir in breadcrumbs until mixture holds together. Season with salt and pepper and set aside to cool completely.
Sift flour and salt into a mixing bowl and make a well in the center. Combine vegan butter and water in a saucepan and bring to a boil until melted.
Pour hot liquid into flour well and mix quickly with a wooden spoon until a rough dough forms, then knead gently until smooth while still warm.
Set aside a quarter of the dough for lids and divide the rest into 6 equal pieces. Press each piece into pie molds or muffin tin cavities, keeping walls an even thickness and reaching slightly above the rim.
Spoon cooled filling into each pastry case, pressing down gently and filling almost to the top.
Roll out reserved dough, cut 6 lid circles larger than the top of each pie, brush edges of pastry bases with plant milk, place lids on top, and pinch edges firmly to seal. Cut a small steam vent in each lid.
Preheat oven to 375°F (190°C). Brush tops with plant milk and bake on a baking sheet for 45-50 minutes until deeply golden brown. Cool in tin for 15 minutes then transfer to a cooling rack to cool completely.
Whisk agar agar powder into vegetable stock in a small saucepan, bring to a gentle boil and simmer for 2 minutes until slightly thickened. Let cool until warm but pourable.
Using a small funnel or spoon, pour the jelly mixture through the steam vent into each cooled pie. Refrigerate for at least 2 hours to allow the jelly to set fully before serving.