Jalapeño blueberry sauce beef burger

Ingredients

• 400 g ground beef
• 1 egg
• 1 tablespoon breadcrumbs
• 1 tablespoon flour
• salt
• black pepper
• 1 tablespoon butter
• 50 g blueberries
• 1 teaspoon sugar
• 3 tablespoons homemade mayonnaise
• 1 tablespoon heavy cream
• 1 clove garlic, minced
• 1 teaspoon finely chopped red jalapeño
• 1/8 red cabbage, finely chopped
• 1 shallot, cut into thin slices
• 2 tablespoons vegetable oil
• 1 tablespoon honey
• 1 teaspoon lemon juice
• 4 buns
• 2 pickled cucumbers
• lettuce
• 4 tablespoons crispy onions