Savory Rhubarb Onion Sauce

Featured in: Flavor Boosters for Any Dish

This sauce features tart rhubarb balanced by the sweetness of maple syrup and depth from red onion and garlic. A splash of balsamic vinegar brings brightness, while fresh basil leaves infuse a fragrant herbal note. Once simmered, the rhubarb melts into a smooth, silky texture. Serve tossed with warm pasta, drizzled over grilled vegetables, or as a flavorful topping for hearty mains. Its unique blend of savory and tangy flavors elevates both simple and elaborate dishes.

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Updated on Tue, 17 Jun 2025 15:12:19 GMT
A bowl of red fruit. Pin it
A bowl of red fruit. | tastygusto.com

This savory rhubarb sauce is my go-to when rhubarb is in season and I want something with a tangy twist that works for both weeknight dinners and special gatherings My family loves it spooned over pasta or even with roasted veggies and it always disappears faster than I expect

I was first inspired to create this sauce after coming home from the farmers market with more rhubarb than I knew what to do with Now my friends always ask for a jar when I have extra

Ingredients

  • Olive oil: Adds richness to the sauce and helps create a silky base For the best flavor use extra virgin olive oil
  • Red onion: Offers a mellow sweetness and color Look for onions with firm outer skins and no soft spots
  • Garlic: Delivers depth and aroma Choose plump cloves without sprouts for the best flavor
  • Rhubarb: Brings vibrant tartness Thinly slice the stalks and make sure they are bright and firm Avoid any with limp or brown parts
  • Water: Helps soften the rhubarb as it cooks Use filtered water for a clean taste
  • Balsamic vinegar: Adds tang and complexity Go for a good quality aged balsamic if you can
  • Maple syrup: Balances the tartness with natural sweetness Taste and adjust the amount for your preferred level
  • Fresh basil leaves: Give an aromatic finish Use fresh not dried for the brightest flavor

Step-by-Step Instructions

Prep the aromatics:
Finely chop red onion and mince garlic This makes sure they cook down evenly and release their full flavor Start with fresh ingredients for the best taste
Sauté the onion and garlic:
Pour olive oil into a medium pot and set over medium low heat Add onion and garlic Stir frequently and let it soften slowly for about eight minutes Wait until the onion turns translucent and sweet before moving to the next step
Add rhubarb and other ingredients:
Stir in the sliced rhubarb then pour in water Add balsamic vinegar and maple syrup Tear the basil leaves and add those too Bring the whole mixture to a gentle boil
Simmer to perfection:
Once boiling lower to a gentle simmer Let the mixture bubble for around ten minutes Stir occasionally You want the rhubarb completely dissolved into the sauce and the texture to thicken Do not rush this step as it helps the flavors blend
Taste and adjust:
Taste your sauce and add more maple syrup if you like a sweeter note Simmer a little longer if it still looks runny The finished sauce should be glossy thick and pourable Let it cool slightly before serving
A fork is on a plate with pasta and meat. Pin it
A fork is on a plate with pasta and meat. | tastygusto.com

I am always amazed at how the tart rhubarb transforms into this silky blend The aroma of basil in the finished sauce reminds me of my grandma’s kitchen in early summer when the herb beds were at their peak

Storage Tips

Store any leftover sauce in an airtight glass jar in the refrigerator It keeps well for about five days Reheat gently on the stove or in short bursts in the microwave for best texture If making a large batch you can freeze portions in small containers and thaw overnight in the fridge

Ingredient Substitutions

You can swap red onion for yellow or shallots with slightly different sweetness If you do not have fresh basil try flat leaf parsley or even a touch of fresh tarragon For a bolder note add a tiny pinch of chili flakes during the simmer

Serving Suggestions

This rhubarb sauce is especially good spooned over spaghetti tossed with grilled zucchini or served as a topping for grain bowls It also makes a creative base for pizza or a condiment on a veggie burger I have set jars out with a cheese and charcuterie board and everyone comments on its unique taste

A bowl of spaghetti with meatballs and basil. Pin it
A bowl of spaghetti with meatballs and basil. | tastygusto.com

This rhubarb sauce is perfect for when you want something unique yet simple that everyone will love

Frequently Asked Questions

→ What dishes pair well with savory rhubarb sauce?

This sauce complements pasta, roasted vegetables, grilled meats, or even as a spread for sandwiches.

→ Can I use frozen rhubarb instead of fresh?

Yes, frozen rhubarb works well. Defrost first and drain any excess liquid before adding.

→ How sweet or tangy is the sauce?

The maple syrup balances rhubarb's tang. Adjust the sweetness by using more or less syrup to taste.

→ Is the sauce suitable for vegans?

Yes, all ingredients are plant-based and suitable for vegan diets.

→ Can the sauce be made ahead?

Prepare in advance and store in an airtight container in the fridge for up to 5 days.

Savory Rhubarb Onion Sauce

Bright and tangy rhubarb pairs with onion and basil in a uniquely savory sauce.

Prep Time
10 Minutes
Cook Time
18 Minutes
Total Time
28 Minutes

Category: Sauces & Marinades

Difficulty: Easy

Cuisine: Contemporary European

Yield: 4 Servings (Approximately 350-400 ml sauce)

Dietary: Vegan, Vegetarian, Gluten-Free, Dairy-Free

Ingredients

→ Main Ingredients

01 2 teaspoons olive oil
02 1 red onion, finely chopped
03 2 garlic cloves, minced
04 3 large rhubarb stalks, thinly sliced
05 80 millilitres water
06 1 tablespoon balsamic vinegar
07 2 to 3 tablespoons maple syrup, to taste
08 6 fresh basil leaves

Instructions

Step 01

Heat the olive oil in a pot over medium heat. Add the chopped red onion and minced garlic, sautéing for about 8 minutes until soft and fragrant.

Step 02

Stir in the sliced rhubarb, water, balsamic vinegar, maple syrup, and basil leaves. Bring the mixture to a boil, then reduce heat and simmer for 10 minutes, stirring occasionally, until the rhubarb is completely softened and the sauce has thickened.

Notes

  1. Serve this savory rhubarb sauce with pasta, grilled vegetables, or as a condiment alongside roasted dishes.

Tools You'll Need

  • Medium pot
  • Wooden spoon
  • Chopping board
  • Kitchen knife

Nutrition Facts (Per Serving)

It is important to consider this information as approximate and not to use it as definitive health advice.
  • Calories: 68
  • Total Fat: 2.5 g
  • Total Carbohydrate: 16 g
  • Protein: 0.7 g