Byzantium 1.5

1. Make your ruler a military leader.
2. Take mission "Improve our Prestige!".
3. Rival the Ottomans.
4. Break vassalization of Athens.
5. Delete two of your infantry regiments in Constantinople.
6. Fabricate a claim on Burgas.
7. Start building galleys in each of your three provinces.
8. Unpause.
9. Send one of your infantry regiments in your capital to Achaea with your fleet.
10. You have one (1) barque. Send it to the straits of Otranto.
11. Send your main fleet back to Constantinople.
12. Order your main fleet to patrol between Constantinople and the Sea of Marmara.
11. Attack Albania with the Reconquest CB.
12. Wait a couple of months until your war score allows you to vassalize Albania. Do it.
13. The next years are going to be very tough for the Albanians. Apologize to them.
14. You are now the war leader against the Ottomans. Scorch earth in Achaea and Constantinople.
15. Invade Anatolia with your stack consisting of 1k infantry and 1k cavalry. The Ottomans may still have a leaderless 1k cavalry regiment in Anatolia. Destroy it. Once Anatolia is free of Turkish troops, split your 2k stack and send the infantry regiment back to Constantinople.
16. Loot Anatolia with your horse and use the money to build more galleys in all your provinces. Keep building galleys until your total fleet numbers at least 20 ships; up to 25 are preferable.
17. When the Ottomans are done sieging Albania, they'll send their 17k fleet to the Ionian Sea to blockade Achaea. Normally, the Ottomans would send their fleet to the Bosporus; however, since a single looting regiment like yours in Turkey isn't interpreted as a danger by the AI - which is true, as one regiment is not enough to siege a province - they are perfectly content with blockading the nearest port.
18. The two main stacks of the Ottomans are now patiently waiting in Epirus, Athens, Silistra and/or Edirne for the Scorched Earth modifier to end. If you had more than one regiment stationed in Constantinople or Achaea, they would attack without second thought. However, the Ai doesn't consider killing 1 regiment worth entering a province that has been scorched. Keep an eye on the Scorched Earth modifier and immediately re-scorch the two provinces as soon as it disappears.
19. Repeat step 16 and 18 until you have enough galleys to challenge the Ottoman fleet.
20. Equip your galleys in Achaea with an admiral. Recruit a naval reformer if you have one available.
21. Send your galleys in Morea to Constantinople and merge them with your main fleet.
22. Send your main fleet to the Ionian Sea to stomp the Ottoman ships. As soon as your fleet enters the Sea of Crete, the Ottoman ships will retreat. Use your galleys in Achaea to intercept them until your main fleet comes to the rescue a couple of days later.
23. Victory (despite their likely god-like naval leader)! Rebuild galleys if you suffered big losses.
24. Blockade all Ottoman ports. Be careful though - the AI tend to rebuild ships too.
25. Build four (4) infantry regiments in Constantinople. Send them to Anatolia one by one. Don't forget to keep an infantry unit in your capital for scorching duties.
26. Use your four infantry units to siege two provinces at a time. Do not siege Kutahya. Continue looting with your horse for good measure.
27. Peasant revolts will sooner or later emerge in the provinces you just occupied. Open the diplomacy window and use "Support rebels" to, well support them. Give them as little money as possible. They are now on your side and will refuse to siege the provinces occupied by you. Let them have Kutahya. If the Ottomans discover your rebel support, support them again.
28. With their armies trapped in Europe, there's little the Ottomans can do. The same is true for you too - you can't enter Europe just yet. Keep sieging provinces and Wait for their war exhaustion rise. With half of their country occupied and 100% blockaded ports, WE should accumulate fairly quickly.
29. Keep an eye on the military ledger. With their country in such a disastrous state, the Ottomans won't be able to sustain their economy forever, eventually leading to bankruptcy. Their entire army will be disbanded when they go bankrupt. Now's your time to strike!
20. Enter the Balkans with your units. The AI knows how to use harsh treatment, so there's a good chance there are no Greek/Orthodox rebels yet. However, harsh treatment gets nullified if the harshly treated province gets occupied by somebody else. Siege Edirne and when you're done with it, wait for rebels to appear there and let them do the dirty work for you.
21. Meanwhile, you can reconquer Athens.
22. Do not, under any circumstances, retake Albania. Lifting the occupation of Albania will make the nasty "Call for Peace!" modifier appear. Be patient and wait for rebels to spawn and your provinces to defect to you.
23. If Albanian patriots or orthodox zealots spawn in Albania, you're out of luck since they are considered friendly troops so you can't fight them. If the "Call for Peace!" modifier appears and turns into a problem and Greek patriots still haven't shown up, siege Greece yourself and take what's yours in the peace deal.

In any case, the Turks are now devastated and with your new strength you should have an easy time restoring the Roman Empire.

Pro tips:
Rhodes might defect to you all by itself. If the Mamluks snatch Cyprus - and they usually do - they'll probably fabricate a claim on Rhodes and attack you. Make sure your fleet is large enough to counter theirs. This is an easy war that will allow you to reconquer your core Cyprus.
Remember how we fabricated a claim on Burgas? If Bulgarian nationalists appear and free Bulgaria from the shackles of the Ottoman Empire, attack and vassalize them ASAP. Return their cores in the peace deal with the Ottomans should the war score allow it.
The Anatolian beyliks are very likely to fabricate tons claims on the Ottomans. Check their claims on the diplomacy map, vassalize your beylik(s) of choice and feed them the good Ottoman stuff - they're hungry.