Mince the onion into 1 cm. Peel the garlic, remove the hard ends, cut in half and then use the flat side of the knife to crush.
Add olive oil and the garlic from Step 1 into a pot and cook on low heat for 20 minutes. Occasionally, stir from the bottom to make sure it doesn't burn.
Add the ◎ ingredients and cook on low heat for another 20 minutes, stirring occasionally.
Once the liquid has evaporated and it has a nice gloss, it's done. This is a tomato sauce base, which has a nice sweetness and richness without soup stock.
Here I added shrimp, squid, and a bit of white wine and cooked with the tomato sauce. Then I poured it over pasta.
Add a little bit of salt and it also works as a pizza sauce. (For the pizza dough check out Recipe ID: 1198384)
A recipe variation. Homemade Meat Sauce (Recipe ID: 924185)
Story Behind this Recipe
This is a recipe I got from a cooking specialist that I really respect. I've made this countless times over the past 10+ years and added my own spin. It's a very special recipe.
Above all else, it's very crucial to simmer the onions for 20 minutes. This is what brings out their sweetness. Since you'll be simmering over low heat, it won't stick to the pan. But be sure to mix from the bottom occasionally! I always make twice the amount and freeze leftovers.