In a medium fry pan, add the olive oil and heat to medium.

Spread the diced onions in a layer in the frying pan.

Cover, turn down the heat and slow cook the onions until they are translucent.

Stir often so the onions don't burn. Don't rush the onions. If they take 30 minutes or more it is no worries. The slower they cook the sweeter they get.

Meanwhile, prep the birdseye chili. This step is up to you. You can put it in the onions whole and remove before mashing (mild). For spicy, remove the stem and carefully dice - tipping in the seeds and all.

Once the onions have been on the heat for about 10 minutes, stir in the garlic and chili. Put the lid back on and let it all slow cook.

Drain the canned beans.

In a large bowl, put one can of the drained beans. Add half of the onion mixture and mash (or whizz with a stick blender). This helps the beans all stick together for things like burgers and tacos.

Carefully stir in the remaining 4 cans of drained beans and the rest of the onion mixture. Cool to room temperature then cover with plastic wrap and keep in fridge until ready to use.