200 gm mortadella, thinly sliced

Tomato sauce:
400 gm canned tomatoes
80 ml (1/3 cup) malt vinegar
30 gm brown sugar
1 garlic clove, bruised
1 cinnamon quill
1 fresh bay leaf
1 tsp coriander seeds
To taste: Tabasco

Potato bread:
1 small Dutch cream potato (about 120gm), scrubbed
185 ml milk, at room temperature
55 gm caster sugar
7 gm (1 sachet) dried yeast
500 gm bread flour
1 egg
1 egg yolk
75 gm softened butter, chopped

For tomato sauce, place ingredients, except Tabasco, in a large saucepan and bring to the boil, then reduce heat to low and simmer, stirring occasionally, until thickened (2–2½ hours).
Remove cinnamon quill and bay leaf, blend mixture with a hand-held blender until smooth (the sauce should be thick; reduce further if necessary), then stir in Tabasco.
Tomato sauce will keep in an airtight container for 3–4 days.

For potato bread, cover potato in cold water in a saucepan over medium-high heat, bring to the boil and cook until tender (15-20 minutes).
Drain, rinse under cool running water, then peel when cool enough to handle.
Return to saucepan, mash to a purée, then add milk and cook over medium heat, whisking continuously, until slightly warmed through (2-3 minutes).
Combine sugar and yeast in an electric mixer with dough hook attachment, add potato mixture, whisk lightly to combine, then set aside in a warm place until mixture becomes foamy (5–7 minutes).
Mix in flour, egg, yolk and 1 tsp fine salt and knead on medium speed until a smooth dough forms and comes away from the side of the bowl (4-6 minutes).
With the motor running, add butter in batches and knead until dough is smooth, shiny and firm (5–7 minutes).
Cover with a tea towel and rest for 10 minutes.

Preheat oven to 220C and line an oven tray with baking paper.
Divide dough into 16 portions of 30gm, then roll into balls with your hands moistened with olive oil to prevent the dough from drying out.
Place on prepared oven tray, cover with a tea towel and set aside until dough has risen by a third (1 hour).
Bake, turning tray once, until golden brown (15–17 minutes).
To serve, tear open hot buns, slather with tomato sauce and stuff each with 2–3 slices of mortadella.