Keto Stir Fried Bell Peppers with Capers and Olives

⏲ ~16 min total · prep 12 · cook 4 · 4 servings

By the KFI Test Kitchen · Tested & approved by Jason Lieu, KFI recipe editor

Published Sep 15, 2026 · Updated Nov 2, 2026

Ingredients

• 3 medium bell peppers (mixed red and yellow), cored, seeded, cut into 1/2-inch strips
• 3 tbsp olive oil
• 3 garlic cloves, smashed flat with the side of a knife
• 1/4 tsp red pepper flakes
• 2 tbsp capers, drained well
• 1/3 cup kalamata olives, pitted and torn in half
• 1 tbsp sherry vinegar
• 1 tbsp cold butter, cubed
• 1 tbsp chopped fresh parsley

Instructions

1. Heat the olive oil in a 12-inch cast-iron skillet over high until it shimmers and a pepper strip dropped in sizzles hard on contact.
2. Add the peppers in one layer and stir-fry 4 to 5 minutes, tossing every 30 seconds, until the skins blister and spot with char while the flesh stays crisp-tender — no soft, collapsed pepper here.
3. Push the peppers up the sides, drop the garlic and red pepper flakes into the hot oil in the center, and fry 30 seconds, just until the garlic smells sweet and turns blond.
4. Toss in the capers and torn olives with everything and cook 1 minute more; listen for the capers to pop and split open.
5. Pull the pan off the heat, add the sherry vinegar (it will hiss and steam off sharp), then swirl in the cold butter until the pan sauce turns glossy.
6. Taste before salting — capers and olives carry plenty — then finish with the parsley and serve hot.

Why this recipe works

• High heat, short time Cast iron over high heat blisters the pepper skins in 4 to 5 minutes while the flesh inside stays crisp-tender. A cooler pan steams them soft instead, and soft is what this dish refuses to be.
• Brine built in Capers and kalamata olives season the pan on their own, which is why the recipe says taste before salting. Sherry vinegar and cold butter then turn the pan drippings into a glossy sauce with no stock or thickeners.
• 3.6 net carbs The whole pan of peppers and briny add-ins runs 3.6 net carbs a serving, so it fits beside whatever protein is planned. Most of the carbs come from the peppers themselves.

Tips for making this recipe well

Get the pan ripping hot

The oil should shimmer and a dropped pepper strip should sizzle hard on contact before anything else goes in. A lukewarm pan steams the peppers, and steamed peppers never blister.

Tear the olives by hand

Torn olives throw rough edges that catch the pan sauce, and they stay juicier than knife-cut pieces. Pitted kalamatas split in half in two seconds each.

Cold butter, off the heat

Swirl the butter in after the pan leaves the burner so it emulsifies into the vinegar instead of splitting into grease. The sauce should turn glossy within seconds.

Listen for the capers

During that final minute the capers should pop and split. Silence means they went in wet, which also waters down the sauce.

Salt last, if at all

Capers and olives carry plenty of salt between them. Taste a pepper strip first and you will usually leave the salt out entirely.

Serving suggestions

Thirteen minutes and one skillet, and the peppers reach the table while your protein rests. They want a plain partner, roast chicken or seared pork chops, because the capers and olives arrive with plenty of their own salt and tang. Leftovers fold into tomorrow's lunch without apology. For a meatless supper, slide two fried eggs over the top and call it dinner. Serve straight from the skillet while the pan sauce still glosses the peppers, parsley scattered over at the last minute.

Storage and meal prep

Cool the peppers and refrigerate them covered for 3 to 4 days. The skins mellow and the flesh relaxes into the sauce overnight, so day-two peppers spooned over greens make an easy lunch. Skip the freezer here: thawed peppers turn limp and watery; the butter sauce breaks with them. To rewarm, one hot minute in a skillet beats the microwave, which leaves them slumped and greasy.

Variations worth trying

• Green beans instead Swap in a pound of trimmed green beans and give them a minute longer in the pan. Keep the capers and olives exactly as written.
• Milder pan Leave out the red pepper flakes entirely; the dish holds up without them. Half a teaspoon works if your table likes heat.
• Lemon for vinegar No sherry vinegar is no problem. Lemon juice off the heat does the same acid work with a different accent.

Frequently asked questions

Does it need a cast-iron skillet?

Any heavy 12-inch skillet will work. Cast iron holds high heat best, which is what blisters the skins in 4 to 5 minutes, so a lighter pan needs a longer cook and delivers less char.

Should I salt the peppers?

Usually not. Capers and kalamata olives carry plenty of salt, and the recipe says to taste before adding more. Only if your capers were rinsed and the olives mild will you want a pinch.

How spicy is it?

A quarter teaspoon of red pepper flakes warms the whole pan without dominating it. Leave them out for sensitive eaters or double them if heat is the point.

What can I prep ahead?

Cut the pepper strips and tear the olives up to a day ahead, covered in the fridge. The stir-fry itself takes 13 minutes and gains nothing from waiting.

Why add the vinegar off the heat?

Off the heat it hisses and steams off its sharp edge, leaving clean acidity behind. Boiled hard, vinegar tastes harsh and flat.

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