Slice pork belly into bite-sized pieces.

Halve the shiso leaves lengthwise.

Mince or finely chop the garlic.

Combine miso, sake, mirin, and sugar in a small bowl to create the seasoning mix.

Heat margarine in a frying pan over low heat.

Add minced garlic to the pan and gently fry until fragrant.

Increase heat to high and add pork to the pan.

Stir-fry pork until almost cooked through.

Reduce heat to medium and pour the seasoning mix over the pork.

Stir until sauce thickens and reduces slightly.

Add shiso leaves and stir quickly to combine.

Remove from heat and serve immediately.