Rinse, drain and peel ginger; Slice the minority; Grate it with a microplane grater over a bowl.
Put a strainer over a bowl; Line the strainer with a piece of cheesecloth, draping the corners over the sides; Spoon the grated ginger into the center of the cheesecloth; Gather up the 4 corners and twist to squeeze the grated ginger for juice for later use.
Scrape any black membrane on the inside of fish belly off; Rinse it; Pat-dry it with kitchen paper; Cut it into large pieces; Marinate them with seasoning (1) for 30 minutes.
Peel and chop garlic finely.
Rinse and drain spring onion; Cut off any roots; Cut it into sections.
Rinse and drain red chili pepper; Slice off any stem with a vegetable knife; Slice it; Discard any seeds.
Rinse and drain green bell pepper; Slice off any stem; Bisect it lengthwise; Scrape off any seeds; Slice it.
Add seasoning (2) and the ginger juice into a mixing bowl; Mix.
Locate a centre line of a lychee and hold it with thumb and index finger each on either side of the centre line; Gently squeeze it till it cracks; Pull off the shell; Core it (repeat the step for each lychee)
Add 5 tbsp cornstarch into a flat plate; Evenly dust the fish pieces with the cornstarch.
Add 4 tbsp oil to a nonstick casserole; Heat it over a high heat; Turn to a medium heat; Arrange the fish pieces into the casserole; Pan-fry them over a medium heat till both sides are slightly brown; Set the fish pieces aside; Drain them; Turn off the heat.
Set the oil aside, leaving 1 tbsp oil in the casserole; Add the garlic and the ginger; Stir-fry it over a high heat till fragrant; Turn to a low heat; Add the green bell pepper, the red chili pepper, most of the spring onion and the seasoning (2); Stir-fry it over a low heat till the sauce thickens; Return the fish pieces to the casserole; Cook over a low heat for 6 minutes; Turn off the heat; Add the lychees and the pineapple; Toss them gently; Arrange them on a serving plate; Garnish them with the remaining spring onion; Ready to serve.