1. Cook your sushi rice using your preferred method – I usually just use my rice cooker and added about 1cm water above the rice grain level.
2. Make the unagi sauce: in a pot mix together the mirin, sake and sugar then bring it to the boil.
3. Once the sugar has dissolved, gradually add the soy sauce and mix until it’s well blended.
4. Reduce to low heat and simmer for about 10 minutes or until it thickens. The sauce will bubble up intermittently. If it becomes too thick, add a tiny bit of water to loosen it up. It should have a slightly syrupy texture. Once done, put aside to cool down.
5. Preheat the oven on BROILER mode (oven heat from above) at 200 degrees and line a baking tray with some foil.
6. Unagi fillets are usually sold in a long piece, I’d recommend cutting it in half (as pictured) so that it can easily fit your bowl. Place the unagi filets on the baking tray in the oven for about 5-6 minutes
7. Take the fillets out and brush some of the unagi sauce that you have prepared on top then return to the oven for another 2-3 minutes until the sauce starts bubbling up (be careful to not leave in the oven for too long otherwise it will burn because of the high sugar content)
8. Assemble: in a bowl, add the cooked rice, brush it with some remaining sauce and then lay the fillet on top.
9. Optional: I like to add some garnishes such a sesame seeds and nori flakes on top.

If you have leftover sauce, you can just save it in a sealed container in the fridge until next use.