Mix 1 clove of crushed garlic and 1 teaspoon of crushed peppercorns together in a small bowl. Press a small amount of the mixture on both sides of the steaks.
Prepare a large nonstick skillet with olive oil cooking spray and place over medium heat. Arrange steaks in a single layer.
Cook the steaks until they are beginning to firm and are hot and slightly pink in the center, about 5 minutes per side. An instant-read thermometer inserted into the center should read 140 degrees F (60 degrees C). Remove the steaks to a serving platter and keep warm.
Cook and stir the green, red, and yellow bell pepper strips, the onion, and 1 clove of minced garlic in a clean skillet sprayed with olive oil cooking spray over medium heat until onion is translucent, about 5 minutes; transfer vegetables to a bowl.
Mix the beef bouillon granules, red curry powder, 1/2 teaspoon of crushed peppercorns, evaporated milk, and water into the skillet. Cook and stir over medium heat until the bouillon granules have dissolved.
Continue to cook the sauce, stirring often, until reduced to 1/2 cup, about 10 minutes; stir in the bell pepper mixture and heat through.