Microwave Baked Onions in Tomato & Basil Sauce

This is an easy recipe that can be a side dish as half an onion, or the main meal with more halves and the addition of some extra grains/pasta/etc to soak up the sauce. No animal products or gluten required.

Serves 3-6 (half or a whole onion) and costs about AU$2 (as of November 2025).

Based on the “Baked Onions” recipe in an old Family Circle Kids Microwave Cooking book I had as a kid.

Microwave Baked Onions in Tomato & Basil Sauce

Gear

You will need a microwave safe casserole dish (glass or ceramic) with a loosely fitting lid, enough to keep most of the steam in the dish. Also requires small mixing bowl, mixing spoon, knife, chopping board and good oven gloves for holding a scalding hot object.

Ingredients

  • 3 medium Onions

  • 300g Passata or 100g Tomato Paste Concentrate + 200ml Water

  • 10ml (generous dash) Extra Virgin Olive Oil (optional, but improves richness of the sauce. Taking it out cuts out ~25% of the calories)

  • 1 heaped tsp Minced Garlic

  • 1 tsp basil

  • 1 tsp parsley, majoram or oregano

  • 1/2 tsp Sweet Paprika

  • 1/2 tsp Tumeric

Optional: Extra veggies can be added into the sauce to make it a more substantial meal. Small stuff like peas & corn goes well, so do well diced carrots, celery, capsicum etc.

Method

6 onion halves placed large side down in a dish.

  1. Top & tail onions, peel and cut in half.

  2. Place them cut side down in a glass/ceramic casserole dish (see photo above).

  3. Mix all other ingredients together in a bowl to make the sauce, then pour over the onions.

  4. Cover and cook on high for 5 minutes.

  5. Turn onions over (cut side up) and spoon some sauce over each. (If space allows, do this within the microwave so you don’t have to take it out while it’s hot and risk fumbling it)

  6. Cover and cook for a further 5 mins on high.

Be careful removing from the microwave, it will be steaming hot. If possible, let it cool down before handling.

Nutrition

Each half-onion with 1/6th of the sauce has 0.29 212 kilojoules (51 kilocalories), 1.6g protein, 2.0g fibre, 6.1g carbs and 1.9g fat.

If you leave out the olive oil, each 1/6 has the same amount of protein, fibre and carbs, but only 155 kilojoules (37 kilocalories) and 0.4 g fat.