This creamy onion dip is perfect for dinner with toast or serve with tortilla. Easy to make and you need only few ingredients. Toss the chopped onions and garlic with 2 tbsp. oil in a frying pan, and season with salt and pepper. Roast, turning occasionally, until soft and light yellow, about 10 minutes; set roasted onions aside to cool.
Place roasted onions in a food processor add the mustard and butter and puree until smooth. Transfer to a bowl and serve with toast.