This will change the flavour somewhat
Cut onions in half
slice them into very very thin half-rounds
remove some of the fat from the stew and use that to fry these onions, it will take more fat than one expects.
The onions will soften then start turning colour.
This stage is critical, stir so that instead of burning, the colour transition from golden through caramel to deep rich brown.
Once brown, remove with slotted spoon. drain as much oil as possible. then crush...