Easy and healthy potato salad

• 1 kg potatoes
• 1 onion
• 1 green bell pepper
• 1 red bell pepper
• 60 g Borges green olives
• 200 g canned tuna
• 4 eggs

For the sauce:

• 200 ml Borges almond drink
• 2 tbsp mustard
• A pinch of salt
• 300 ml Borges extra-virgin olive oil
• ½ lemon